ăcerbo — Lewis & Short
ăcerbo, āvi, ātum, 1, v. a.id. (vox Vergil.).
I To make harsh or bitter, to embitter; lit. and trop. (very rare):
gaudia,Stat. Th. 12, 75:
mortem,Val. Fl. 6, 655.— Hence in an extended sense,
II To augment or aggravate any thing disagreeable (cf. acuo):
formidine crimen acerbat,Verg. A. 11, 407:
nefas Eteoclis,Stat. Th. 3, 214.