Green’s Dictionary of Slang

1. (W.I./US black/US campus) an amazing thing; also attrib.

1997–2000		College Sl. Research Project (Cal. State Poly. Uni., Pomona) 🌐 Bashment (noun) An event which is da bomb. [Immaculate Conception, Jamaica, W.I.].
2008		A. Wheatle Dirty South 31: She still stepped to the latest bashment dances.

2. (UK black) loud, energetic music.

2005

Jade LB Keisha the Sket (2021) 55: [We] wer greeted wit bashment playin an a whole leepa blck ppl dancin.