A swinger is a person who is in a romantic relationship but also has sex with other people.
The word swinger can make people think of excitement, freedom, and sometimes of disapproval or shock.
Examples:
The swingers went to a party together.
She is a swinger and has many friends.
The swinger likes to meet new people.
The swinger's parties are always fun.
In the town, everyone knows about the swinger.
The swinger's life is very different from mine.