noun
friend with benefits; fuck buddy
Casual abbreviation of セックスフレンド. Used among younger speakers to refer to a sexual partner without romantic commitment. Can sound crude or flippant depending on context.
See also: セックスフレンド
あの二人、付き合ってるわけじゃなくて、ただのセフレらしいよ。
Those two aren't dating; apparently they're just friends with benefits.
セフレを作るより、ちゃんと恋人を探したい。
Rather than finding a fuck buddy, I want to look for a real partner.