You probably know several people with your own birthday. Because you only have 365 options for dates, two people who know each other might share a birthday. But what is the term for this? This article will present several words you can use for two people with the same birthday.
The preferred words for someone who has the same birthday as you are “Birthday twins”, “Cosmic twins” and “Coetaneous”. “Birthday twins” is simply the most popular of all these terms. “Cosmic twins” has a specific flair that makes it hard to ignore, and “Coetaneous” is a very accurate descriptor.
“Birthday twins” is a fantastic term to use for someone who has the same birthday as you. While there is no precise term that refers to this situation in English, “Birthday twins” comes the closest, as it’s an expression that everyone will understand.
When you use “Birthday twins”, the word “twins” is signaling the fact that you share some sort of bond with this person.
Therefore, “Birthday twins” merely serves as a good way for people to immediately understand that you share a birthday with this particular person.
Here are a few example sentences that showcase the proper way to use “Birthday twins” in a conversation:
- She was born on the exact day as me, which I’m fairly sure makes us birthday twins.
- Real biological twins are always birthday twins as well, when you think about it.
- They were both birthday twins with each other, which was a very interesting coincidence.
- I met this guy the other day at a party and it turns out we’re absolutely birthday twins.
“Cosmic twins” is another great alternative that you can use to refer to someone who has hte same birthday as you. The real appeal of “Cosmic twins” as a term you can use is its specific flair: It brings to mind the universe, and how mysterious powers made you two share a birthday.
While “Cosmic twins” might not be the most formal or precise term for two people who share a birthday, and it is in fact quite a dramatic term, it’s still immensely useful to convey the concept to someone else.
You can use “Cosmic Twins” in a casual conversation, and it will allow you to use an expression that has a lot of artistic flair.
Here are some example sentences that will teach you how to properly use “Cosmic twins” in a sentence:
- She and I are cosmic twins, which if you don’t know, means that we were born on the same date.
- They were both cosmic twins of each other, though they wouldn’t find this out until later.
- When you’re someone else’s cosmic twin, it means that you share a birthday at the very least.
- Looking at both of our application files I realized that you and I are actually cosmic twins!
An underappreciated word that you can use to refer to someone who has the same birthday as you is “Coetaneous”. This is a word that’s mainly utilized to say that two things are of the same age, that they happened around the same time.
Therefore, you can easily say that your birth and someone else’s were “Coetaneous” events, and just with that adjective you’re communicating the fact that you and the person were born at the same time.
Many people aren’t familiar with the term “Coetaneous”, which is a shame because it’s quite a useful word that could be used to describe not just two people with the same birthday, but plenty of other events.
Here are some example sentences that will showcase the way to use “Coetaneous” in a sentence:
- We might not show it, but we were born at the same time, which makes our births coetaneous.
- Your birthday is actually an event that was coetaneous with her birthday.
- His coetaneous birth occurred at the same time as her birth, which is interesting.
- Our births happened at the same time, in a coetaneous fashion, if you didn’t know.
“Birthdate twins” is another good way to refer to two people that share a birthday, be it two random people or you and someone else. “Birthdate” is a useful term because it specifies that the thing you share is the entire date, and not just the day.
While “Birthday twins” is a more popular term that’s similar to this one, the real value of “Birthdate twins” is the fact that, because it’s “Birthdate” and not “Birthday”, you immediately know that the entire date is shared, down to the year.
You can therefore use “Birthdate twins” in a sentence, and not only will people immediately understand what the term means, but also that you and the person you’re referring to were born on the exact same day, month and year.
Here are a few example sentences for “Birthdate twins” showcasing how to use this term:
- Though he looks significantly older than I do, we’re actually real life birthdate twins.
- My birthdate twin is a woman I met at a social gathering a few months ago.
- It’s useful to understand that, because we’re birthdate twins, we’ve lived the exact same time.
- He’s my birthdate twin, as it turns out, which means we’re the same exact age.
A great alternative term you can use for someone who shares a birthday with you is “Birthday buddy”. This is a more casual and less precise alternative, but it’s a good way of conveying that someone was born on the same date as you were.
Part of why “Birthday buddy” is such a good term to use is the fact that when you look at the term, it’s alliterative, which means that both words in the phrase start with the same letter.
The fact that it is alliterative makes it a very catchy and memorable phrase to use, which is sure to stick in the minds of the people who you say it to.
These are a few sentences that contain proper use of the term “Birthday buddy”, for your perusal:
- She’s my birthday buddy, if you can believe it, we were both born August 2nd, 1999.
- This might come as a shock to you, but we’re birthday buddies, you and I.
- My best friend since high school is also my birthday buddy, which is very convenient.
- It’s nice to have a birthday buddy if you both have no one else to celebrate your birthday with.
An alternative term for someone who has the same birthday as you that you might not know about is “Time twins”. This one is great because it’s extremely precise, as it means that not only were you born on the same date, but at the exact same time, as well.
Evidently, “Time twins” are fairly rare, but on the occasion that they do pop up, it’s very useful to already be familiar with the term that describes two people who were born on the same date and time as you were.
While this means that “Time twins” won’t be your most used term, because of how rare the thing it describes is, it’s still worth knowing about.
Here are some example sentences that will show you how you’d use “Time twins” in a sentence:
- They were both born in the same county in 1995, time twins, of all things.
- I realized the other day that we’re time twins, you know, born at the same time.
- You’re born at the same time as dozens of other babies, so you have a lot of time twins.
- Though he’s my time twin, born at the same time as me, I don’t know anything else about him.
A field that deals in the area of birthdays is that of astrology. An astrological term that you could use to refer to someone who has the same birthday as you is a “Star Twin”, which would work because they will have the same star sign as you do.
If someone is born in the same general period as you were, you will share a star sign. This means that if someone is born on the same exact day as you, it’s an irrefutable fact that you will have the same star sign as them.
Therefore, you can refer to people born on the same day as you as your “Star twins”, as you will have the same star sign.
Here are some example sentences that have the proper use of “Star twins” in them:
- We’re total star twins, obviously, because we were both born on the same day.
- I think that if you and her were both born December 2nd, you’re star twins.
- You have to acknowledge that the fact that you’re star twins changed your mind about this.
- I think it’s nice to discover that a friend is actually your star twin because you share a birthday.
A somewhat more advanced and spiritual term you could use to describe someone who shares a birthday with you is “Co-star”. This is an astrological term, which makes sense once you think about how much of astrology is rooted in studying birth dates and times.
If someone is your “Co-star”, what that means in practical terms is that you both share a star sign. If someone shares a birthday with you, then it’s a given that you have the same star sign, making this a useful term in that scenario.
While the term co-star is obviously not limited exclusively to people with the same birthday as you do, it’s nonetheless worth bringing up in the conversation.
Here are some examples of sentences that contain this use of “Co-star” in them so you can use it too:
- My co-star, Jennifer, was born on the same date as me way back in 1992.
- If what you told me about his birthday is true then that makes us co-stars.
- You have to realize that we’re both co-stars and there’s no changing that.
- A co-star can be someone who shares your birthday, obviously.
A catchy, quirky term you can use for someone who shares a birthday with you is “Astro pal”. This particular phrase is very casual and informal, and is born from the fact that if you share a birthday with someone, then that means that you share a star sign in astrology.
This means that when someone is your “Astro pal”, they’re your astrology friend, which is a fancy way of saying that you share a star sign.
The usage of “Pal” to mean friend means that this is a very casual and laid-back way to refer to someone who shares a birthday with you.
Here are some example sentences that showcase the term “Astro pal”:
- She’s my astro pal, we met in the first grade and found out we have the same birthday.
- You could consider him your astro pal if you just share a star sign, though a birthday is better.
- My astro pal is this old guy who I met a couple of years ago at the bank, and we share a birthday.
- I don’t think that this astro pal of yours is good news, even if you have the same birthday.
Martin holds a Master’s degree in Finance and International Business. He has six years of experience in professional communication with clients, executives, and colleagues. Furthermore, he has teaching experience from Aarhus University. Martin has been featured as an expert in communication and teaching on Forbes and Shopify. Read more about Martin here.