significant other

Từ điển WordNet v3.1 - WordNet Dictionary

noun

a person (not necessarily a spouse) with whom you cohabit and share a long-term sexual relationship
• Syn:
domestic partner, spousal equivalent, spouse equivalent
• Hypernyms:
person, individual, someone, somebody, mortal, soul
• Hyponyms:
lover, spouse, partner, married person, mate, better half