what is an irish twin

An Irish twin is a slang term for siblings born less than a year apart, often close enough to be in the same school year. It’s not a medical term, and the phrase can be considered outdated or mildly offensive because of its ethnic stereotype origins.

Quick meaning

• Two siblings born within 12 months of each other.
• Sometimes used for children born in the same calendar year.
• Not actually twins, since they come from separate pregnancies.

Sensitivity

The phrase has historical baggage tied to stereotypes about Irish families, so many people avoid it in favor of more neutral wording like “siblings born close together” or “babies born a year apart”.

Example

If one child is born in March and the next is born the following February, people might call them Irish twins because they’re less than a year apart.

If you want, I can also give you the origin of the term in plain English.