What is Significant Other?
1.
Partner in a relationship; mate or spouse; boyfriend or girlfriend; companion.
Josie is Keith's significant other.
2.
Your mate, spouse, husband, wife, boyfriend, girlfriend, steady and/or lover. Used when you don't want to be too specific, or when the details are nobody's business.
Why's Roger always talking about his significant other? Why don't he just say girlfriend?
Because his "girlfriend" is a guy named Bruce.
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3.
when you're "dating" only one person, but the official title of boyfriend/girlfriend does not exist.
karen: so you and nick are dating?
me: no. he's my significant other.
karen: what's that?
me: we only see each other but we don't have the official title. i.e. he's my significant other.
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