verb

make spitefully critical comments.

everybody was bitching about their colleagues

be spiteful about,criticize,find fault with,run down,cast aspersions on,speak ill of,slander,malign,complain,moan,grumble,grouse,grouch,gripe,knock,pull to pieces,take apart,do a hatchet job on,whinge,bad-mouth,trash,twine,slag off,rubbish