languor.

The noun is derived from Middle English langore, langour (“disease, illness; misery, sadness; suffering; condition or event causing sadness, suffering, etc.; unwholesomeness; idleness, inertia; depression, self-disgust; expression of grief”) [and other forms], from Middle French languer, langueur, langour, and Anglo-Norman langor, langour, langur, Old French langueur, languour (“disease, illness; suffering; emotional fatigue, sadness; listlessness; stagnation”) (modern French langueur (“languor”)), and from their etymon Latin languor (“faintness, feebleness; languor; apathy”), from languēre, the present active infinitive of langueō (“to feel faint or weak; (figurative) to be idle, inactive; to be listless”), ultimately from Proto-Indo-European *(s)leg-, *(s)leh₁g-. The English word is cognate with Catalan llangor, Italian languore (“faintness, weakness; languor”), langore (obsolete), Old Occitan langor (modern Occitan langor), Portuguese langor, languor (obsolete), Spanish langor.

The verb is derived from Middle English langouren (“to be ill; to languish, suffer; to cause to suffer”) [and other forms], from Anglo-Norman langurer and Middle French langorer, langorir, langourer (“to languish; to be languorous”), from Old French languerer, from langueur (“disease, illness; suffering; emotional fatigue, sadness; listlessness; stagnation”); see further at etymology 1 above. Later uses of the verb have been influenced by the noun.