flac ‧ cid /ˈflæsəd, ˈflæsɪd, ˈflæksəd/ BrE AmE adjective technical
[ Date: 1600-1700 ; Language: Latin ; Origin: flaccidus , from flaccus 'soft and loose' ]
soft and weak instead of firm:
a flaccid penis
—flaccidity /flæˈsɪdəti, flæˈsɪdɪti, flæk-/ noun [uncountable]