Meaning of the word plus-one in English

What does plus-one mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

plus-one

US /ˌplʌsˈwʌn/
UK /ˌplʌsˈwʌn/
"plus-one" picture

Noun

a person who accompanies a guest to a social event, such as a wedding or party

Example:
The wedding invitation says I can bring a plus-one.
Are you going to the party alone or do you have a plus-one?