early 14c., "fail in strength, exhibit signs of approaching death," from languiss-, present participle stem of Old French languir "be listless, pine, grieve, fall ill," from Vulgar Latin *languire, from Latin languere "be weak or faint" (see lax). Weaker sense "be lovesick, grieve, lament, grow faint," is from mid-14c. Related: Languished; languishing.