Я-27

СЛАБ (СЛАБЫЙ) НА ЯЗЬНС obsoles, substand AdjP subj-compl with copula (subj: human, both variants) or modif ( var. with long-form Adj) fixed WO

a person who is too talkative, has a tendency to talk unrestrainedly

X слаб на язык - X has a loose tongue

X talks nonstop X has trouble keeping his mouth shut X can't keep his tongue still X is a blabbermouth.