BF

/bˌiːˈɛf/

(especially in text messages, on social media, etc.) a male partner that one has a sexual or romantic relationship with

/bˌiːˈɛf/

(especially in text messages, on social media, etc.) a person's best friend

Examples

1. ac is equal to bf.

2. In 1936, the Bf 109 won the RLM’s fighter contest.

3. Five Bf 109s took part and demonstrated outstanding climbing, diving, and maneuverability, along with exceptional speed.

4. I've gone from FF to BF.