late 14c., from Old French calme "tranquility, quiet," traditionally from Old Italian calma, from Late Latin cauma "heat of the mid-day sun" (in Italy, a time when everything rests and is still), from Greek kauma "heat" (especially of the sun), from kaiein "to burn" (see caustic). Spelling influenced by Latin calere "to be hot." Figurative application to social or mental conditions is 16c.
late 14c., from Old French calme, carme "stillness, quiet, tranquility," from the adjective (see calm (adj.)).
late 14c., from Old French calmer or from calm (adj.). Related: Calmed; calming.