What Does “Mc-” And “O’-” Mean In A Name? Full Explanation!

Some names (especially those of Scottish and Irish origin) start with “Mc-” or “O’-.” This article will aim to help you understand what these two prefixes mean and why they’re so common in certain cultures.

What Does “Mc-” Mean In A Name?

“Mc-” is an abbreviation of the Gaelic term “mac,” which means “son.” When it’s written in a surname, it means that the surname originated from someone with the following name. For example, someone called McDonald would mean “son of Donald.”

The surname is related to the family lineage rather than the direct descendants of the name. So, if someone were called McDonald, it does not mean their father or even their grandfather was known as Donald.

Instead, both their father and grandfather would also share the McDonald surname, showing that there was a Donald a long time ago who started the family tree that all the McDonald’s are a part of.

What Does “O’-” Mean In A Name?

“O’-” is an Anglicized form, meaning “male descendant of.” It does not directly refer to being a “son” of someone, but it means that someone is a male in the family and will be related to the name. For example, someone called O’Connor would mean “male descendant of Connor.”

Just like the “Mc-” variation, there is no need for the father or grandfather to share the name. So, if someone is known as O’Connor, their father does not have to be called Connor.

Instead, the name would date back to more ancient times, where names like “Connor” were given to kings or royalty. The idea is to link back the surname to the original king with that name.

What Is The Origin Of “Mc-“?

It might help if you knew more about the origin, so we’ll look more into “McDonald” (since we’ve already spoken about it).

“McDonald” comes from the old Scottish clan’s name “Dhamhnuill.” While the old name of Dhamhnuill is out of fashion, it is now known to mean “Donald” in modern times. After hundreds of years of language evolution and simplification, “Donald” was the outcome.

“Mc-” itself is just a way to show that someone is a son of “Dhamhnuill.” That means that they would have once been a male member of the clan, but the idea of clans in Scotland is nothing but ancient history today.

What Is The Origin Of “O’-“?

Since we’re talking about “O’Connor” as well, it might help to know more about the origin.

“Connor” is a modernized way of writing “Conchobhair,” who was an old Irish king. Every descendant of this king shared the name “O’Conchobhair” until “Conchobhair” became “Connor” after hundreds of years of simplification.

So, the prefix “O’-” is related to kings and royalty. It means that someone is a male descendant of the king in question, which is why it’s so useful to go back and look more closely into the origins.

Nowadays, anyone called “O’Connor” has some loose relation to the old Irish king “Conchobhair,” and many of them don’t even know about it.

Does “Mc-” And “Mac-” Mean The Same?

There are also plenty of names that start with “Mac-.” The pronunciation is identical to names starting with “Mc-,” but does that mean they are equal?

“Mc-” and “Mac-” mean the same thing. They both come from the Gaelic term “mac,” which means son. Both names mean that someone was once a male descendant or son of a clan, though the names have since become gender-neutral.

Both men and women in today’s world have “Mc-” or “Mac-” surnames. There is nothing wrong with using them in this way because the “son” aspect of both forms is irrelevant.

What Is The Female Equivalent Of “Mc-” And “O’-“?

While women also share “Mc-” and “O’-” names today, that was not always the case. Since “Mc-” means “son of” and “O’-” means “male descendant of,” it’s clear that there should be a female equivalent in there.

The female equivalent of “Mc-” is “Nic-.” It means “daughter” and relates to the same clan names that men would have had back then. The female equivalent of “O’-” is “Ni-,” which means “female descendant of.” Again, it would have been more common back then.

So, the following names might have been more common back when these names had relevant bearings on rulers and clans:

• Thomas McDonald
• Sarah NicDonald

• George O’Connor
• Amy Ni’Connor

As you can see, the female equivalents are not something you come across today. They have been completely removed from the world, with only the “Mc-” and “O’-” variations left around.

While it’s not relevant today, it’s useful to know about!

Why Is The Letter After “Mc-” Or “O’-” Capitalized?

The letter after the two prefixes is always capitalized. This is done for one very specific reason.

You should always capitalize the letter after the prefix in the surnames because they reference another name. You will also find names like “Donald,” “Connor,” “Brien,” and so on after “Mc-” or “O’-,” which shows that there is a long lineage related to that name.

Names are proper nouns, meaning you always capitalize them. You wouldn’t write your first name in the lower case, and the same rules apply when you look at surnames that include these prefixes.

Here are a few examples to help you:

• Correct: Terry O’Riley
• Incorrect: Peter O’connor
• Correct: Mary McGovern
• Incorrect: Sandra Mctavish

As you can see, the name that comes after the prefixes must always be capitalized. It’s just another name, so it’s useful to remember to keep it written like that.

Interestingly, some people who have these types of surnames will also include both parts in their initials. For example, “Terry O’Riley” can choose to initial himself as either “TO” (including only the first letter) or “TOR” (including the “O’-” and the first letter of the name).

Is There A Space Between “Mc-” Or “O’-” And The Name?

There is no need to put a space between the prefix and the name. It is one surname, so you should always write it as a grouped form. No one writers their surname with a space in it when they have “Mc-” or “O’-” present.