the.com/significant other

means A deliberately vague, gender-neutral term for the romantic partner in your life, whether spouse, boyfriend, girlfriend, or something less easily labeled.

from Originally a sober bit of jargon from psychology and sociology — a 'significant other' was anyone who held major influence over your sense of self, like a parent, mentor, or friend. The phrase drifted into everyday use around the mid-20th century as a handy, non-committal way to name a romantic partner without specifying marital status or gender, which made it especially useful once couples stopped fitting neatly into 'husband' and 'wife.' The clinical phrasing is part of the joke now — it sounds like it belongs on a form, not in a love letter.