Significant other is a deliberately neutral term covering any committed partner, without specifying gender, marital status or the exact nature of the relationship. Girlfriend is specific: a female romantic partner, usually unmarried. One is a category; the other names a role within it.
The core difference
- significant other — any committed partner. Says nothing about gender or legal status.
- girlfriend — a female romantic partner, normally unmarried.
Why the neutral term exists
It solves a practical problem for invitations, forms and workplaces: how to refer to somebody's partner without knowing whether they are married, or what gender that partner is, or whether the couple use partner, fiancé or something else. Bring your significant other covers every case without requiring anyone to disclose anything.
Often abbreviated to SO, particularly online.
The alternatives, and their problems
- Partner — the most widely used neutral option, but ambiguous with business partner in professional settings.
- Spouse — neutral, but implies marriage.
- Boyfriend / girlfriend — clear, but can read as casual for a couple together twenty years.
- POSSLQ — Person of Opposite Sex Sharing Living Quarters, a genuine US Census category from 1980 and a good example of how badly this can be done.
The other meaning of girlfriend
Between women, girlfriend often means a close female friend with no romantic sense at all — usage that is common in American English, especially African American English. Context normally resolves it, and the plural is a strong signal: a night out with my girlfriends reads as friends.
Where the term comes from
Significant other began in psychiatry. It was coined by Harry Stack Sullivan in the 1940s to mean any person with major influence on someone's self-concept — a parent, a mentor, anyone. The narrowing to romantic partner came later in general usage, and the broader clinical sense still exists in the literature.
Frequently asked questions
What does significant other mean?
Any committed partner, without specifying gender, marital status or the nature of the relationship. It is deliberately neutral and often shortened to SO.
Why use significant other instead of girlfriend?
Because it covers every case on an invitation or a form without requiring anyone to disclose whether they are married or their partner's gender.
Does girlfriend always mean a romantic partner?
No. Between women it often means a close friend, particularly in American English. The plural is usually the clue.