Abnormal softening or softness of a part or organ. Chiefly in scientific Latin compounds. "mollities cerebri" noun Obsolete. softening of cerebral tissue; encephalomalacia. "mollities ossium" noun now historical. any of various conditions causing softening (demineralization) or destruction of bone, as rickets, osteomalacia, myelomatosis, etc.; an instance or case of such softening.
Early 17th century (in an earlier sense). From classical Latin mollitiēs (sometimes written molliciēs; also mollitia) softness, effeminacy, submission to anal intercourse from mollis soft + -itiēs, variant of -itia.