Skip to Content

What does the O mean in last names?

Have you ever come across a last name that starts with the letter O, like O’Connor or O’Brien, and wondered what the O means? Does it have any significance or is it just another letter? In this blog post, we will explore the origin and meaning of the O in last names.

The Origin of the O in Last Names

The O in last names is mostly associated with Ireland and its culture. In Irish names, the O’ at the beginning of a surname means “grandson of” or “descendant of” in Gaelic. It was a common practice in Ireland for people to take their father’s or grandfather’s name and add the prefix O’ to it. For example, if your grandfather’s name was Brian, and he lived in the 11th century, your last name could be O’Brien, meaning “descendant of Brian.”

According to historians, the use of the O’ prefix began in the 11th century in Ireland. Irish surnames were used to identify families and differentiate them from other communities. The O’ prefix was adopted by many Irish clans to indicate their descent from a particular ancestor.

In later years, some Irish names dropped the O’ prefix, while others merged it with the surname. For example, O’Connell became Connell, while O’Mahony became Mahony. However, the O’ prefix is still prevalent in many Irish names and is a proud badge of honor for many Irish families.

The O’ Prefix and Irish Genealogy

The O’ prefix plays a crucial role in Irish genealogy. It provides a link to a person’s family history and helps trace their ancestry back to an earlier generation. In Ireland, it was customary to use the father’s name to identify a person. Therefore, a person’s last name was not fixed and could change with each generation.

For example, if your grandfather’s name was Michael O’Connor, and your father’s name was Patrick Michael, your last name would be O’Patrick. However, if your grandfather’s name was Thomas O’Brien, your name would be O’Thomas. This practice made it challenging to identify people with the same first name in large families. To differentiate between family members, they used the prefix O’ to indicate their descent from a particular ancestor.

The O’ prefix has also helped Irish people keep their family history alive. It provides a sense of identity and continuity. Many families have passed down their last names from generation to generation, along with stories and legends about their ancestors.

The O’ Prefix and Irish Culture

The O’ prefix is an essential part of Irish culture. It signifies a person’s connection to their family, their heritage, and their country. Many Irish people take great pride in their last names and the history behind them.

The O’ prefix is also prevalent in Irish folklore and literature. Many famous Irish writers, like James Joyce and W.B. Yeats, used the prefix in their writing to evoke a sense of Irish identity and history. The O’ prefix has also been used in Irish music and dance, featuring prominently in traditional Irish music and dance forms like jigs, reels, and hornpipes.


In conclusion, the O’ prefix in Irish last names signifies a person’s connection to their family, their heritage, and their country. It is an essential part of Irish culture and has been used for centuries to identify families and trace genealogy. The O’ prefix is a proud badge of honor for many Irish families and has played a crucial role in keeping their family history and traditions alive.


Why the O is removed in Irish names?

Irish names have a rich and complex history, with many of them tracing their origins back to ancient Gaelic times. One of the most noticeable features of Irish names is the use of the prefixes “O” and “Mac”. The prefix “O” is used to indicate “descendant of” and is followed by the grandfather’s name, while “Mac” means “son of” and is followed by the father’s name. However, over time, the use of the prefix “O” in Irish names declined, and many Irish names today only use the prefix “Mac”.

The main reason for the decline of the prefix “O” in Irish names can be traced back to the 1600s, when English rule in Ireland intensified. During this period, there was a deliberate attempt to suppress Irish language, culture and traditions, and to promote the English language and culture instead. As part of this effort, the use of Irish names was discouraged, and it became extremely difficult to find work if you had an Irish sounding name.

The English government also introduced laws that required Irish people to adopt surnames, and many Irish families that had previously been known only by their first names were given English surnames. The prefixes “O” and “Mac” were also widely dropped during this time, as many Irish people attempted to anglicize their names to avoid persecution.

Furthermore, during the 1800s, many Irish people emigrated to other countries, including the United States, Canada, and Australia. In order to assimilate into their new cultures and avoid discrimination, many Irish immigrants dropped the prefix “O” from their names. As a result, many Irish names today only use the prefix “Mac”.

The decline of the prefix “O” in Irish names can be traced back to English rule during the 1600s and the subsequent efforts to suppress Irish language and culture. This led to many Irish people attempting to anglicize their names to avoid persecution. Furthermore, the emigration of many Irish people during the 1800s also contributed to the decline of the prefix “O” in Irish names.

What ethnicity is the last name O?

The O surname is primarily associated with Korea, and it is considered a Korean family name. The name is written using a variety of hanja characters that include 吳, 五, 伍, 吾, and 晤. Each of these characters has a slightly different meaning and origin that goes back to ancient China. However, each character has become associated with the Korean peninsula through the adoption of Chinese characters in the Korean written language.

According to Korea’s 2015 census, there were 763,281 people carrying the O surname. The name is the 14th most common family name in South Korea and is widely represented across the country. O is not only a surname but is also used as a given name in Korea. Some famous people in Korea that carry this surname are actress Song Hye-kyo, musician Roy Kim, and footballer Oh Beom-seok.

The O surname has an interesting history in Korea, dating back to the Goryeo period of the 10th and 11th centuries. It is said that people who carried the O name were descendants of King Mu of Zhou, an ancient king in China. During the Goryeo period, a person with the surname O was appointed as a chief military officer, and many of his descendants took on the same name in his honor.

The O family played an important role in Korean history, as many members of this family went on to study Confucian philosophy and became high-ranking officials in the government. Some notable figures in Korean history who carried the O surname are Oh Eung-suk, a scholar and philosopher, and Oh Yeong-soo, a painter.

The O surname has its roots in ancient China and has become widely associated with Korea. It has a rich history in Korean culture, and many people in Korea continue to carry this name with pride and honor.

Why do Italian last names end with O?

Italian surnames are known for ending in a commonly used suffix -o. This distinctive feature of Italian surnames has often caused curiosity among people from other parts of the world. The reason behind this phenomenon is a result of the Italian language and its history.

Firstly, Italian is a language that developed from Latin, which was the language of the Roman Empire. The Latin language had a declension system that involved suffixes being added to words to indicate their function in a sentence. In Italian, the use of suffixes is still very common and this includes the use of -o for masculine nouns and adjectives.

The second reason behind the prevalence of -o in Italian last names is related to the history of the Italian peninsula. Before the unification of Italy, the country was divided into many different states, each with its own language, culture and customs. In southern Italy, which was under the influence of the Spanish Empire, surnames ending in -o are common. By contrast, in northern Italy, influenced by various languages such as French and German, surnames tend to end in -i.

Finally, another reason for -o in Italian last names could be explained by the influence of the Roman Catholic Church. Church records of baptisms, marriages and deaths have been kept for centuries in Italy. Priests, who were in charge of these records, often spelled words the way they sounded. In this context, names ending in -o were pronounced with greater emphasis than other surnames and therefore more easily remembered and passed on to descendants.

The use of -o in Italian last names is a distinctive aspect of the Italian language, culture and history. It is a testament to the country’s diverse regional identities and the influence of external languages and cultures. Understanding the origins of Italian surnames is a fascinating way to delve deeper into the history and culture of this vibrant Mediterranean nation.

What surname has an O apostrophe?

The surname with an O apostrophe, also known as the Irish patronymic naming system, has long been a significant part of Irish culture and history. In this system, the O’ prefix denotes “descendant of” or “grandson of” and is followed by the father’s name. For instance, O’Neill means “grandson of Niall,” and O’Connor means “descendant of Connor”.

There are countless surnames in Ireland that carry the O’ prefix, with variations in spelling and pronunciation. Some of the most well-known include O’Brien, O’Donnell, O’Malley, O’Callaghan, O’Grady, O’Sullivan, and O’Dwyer.

The O’ prefix is also used in first names, with male names usually having Mac or Mc prefixes and female names having Nic or Ní prefixes. However, these naming conventions are not as popularly used as they were before.

While the surname with the O apostrophe is primarily an Irish naming practice, it has also spread outside of Ireland. Many Irish emigrants who left the country during the Great Famine of the 1840s carried their O’ surnames with them to foreign lands. Now, people with O’ surnames can be found all over the world.

The O’ surname with an apostrophe has a rich history and cultural significance in Ireland. Many notable people throughout history, including authors, actors, and athletes, have carried these surnames, which continue to be used today by people all over the world.

Why do Scottish surnames start with O?

Scottish surnames are known for their distinctiveness and rich history. Among Scottish surnames, the use of the prefix “O'” is quite common. This prefix appears in many Scottish surnames such as O’Brien, O’Connor, O’Neill, and others. However, the origin of this prefix is not actually Scottish, but rather Irish.

The prefix “O'” is actually derived from the old Gaelic language, which was spoken in Ireland and Scotland many centuries ago. The prefix “O'” was used in Irish surnames to denote “grandson of” or “descendant of” a specific person. For instance, O’Brien means “descendant of Brian” and O’Connor means “descendant of Connor”.

Over time, many Irish people migrated to Scotland and brought their Irish surnames with them. As a result, Scottish surnames began to include the prefix “O'”. This is why many Scottish surnames, especially those on the west coast and in the Highlands, are of Irish origin.

It’s important to note that not all Scottish surnames carrying the prefix “O'” have Irish origins. Some Scottish families simply adopted the prefix as a way to signify their heritage or affiliation with Irish culture.

To summarize, while Scottish surnames are distinctive and have a rich history, the prefix “O'” found in many Scottish surnames actually comes from the Irish language. This is because many Irish people migrated to Scotland and brought their Irish surnames with them, leading to Scottish surnames adopting the prefix “O'”.

Are surnames with an O Irish?

Irish surnames have a long and interesting history that stretches back centuries. One of the most iconic features of Irish surnames is the “O’” prefix that appears in many names. However, what many people may not realize is that these surnames are more than just a fun linguistic quirk – they are an important part of Irish cultural history.

So, are surnames with an O Irish? The answer is yes – in fact, these surnames are some of the most common and well-known in all of Ireland. Names beginning with “O’,” stemming from “Ó” meaning “the grandson of” or “descendant of,” are still among the most common in Ireland. Today, there are hundreds of different surnames that begin with “O’” and represent different families and clans throughout the country.

One of the reasons that these surnames are so prevalent is that the Irish have a long history of strong, tight-knit family structures. In many cases, surnames would be passed down from father to son, creating a long lineage that stretched back through the centuries. This practice allowed families to maintain their identity and heritage over time, even as they faced various challenges and changes.

Four of the most common “O’” surnames in Ireland are O’Brien, O’Sullivan, O’Connor, and O’Neill. Each of these names has its own unique history and story behind it. For example, O’Brien comes from the Irish “O Briain,” meaning “descendant of Brian,” and was the surname of the ancient kings of Munster. O’Sullivan, on the other hand, comes from “O Suilleabhain,” or “descendant of Suilleabhain,” and was the name of a powerful clan in southwestern Ireland.

Surnames beginning with “O’” are an important part of Irish cultural identity and history. They represent a unique and meaningful way of preserving family heritage and passing down traditions from one generation to the next. So, the next time you come across an Irish surname with an O’, you can appreciate the rich history and cultural significance behind it.