"quietness, stillness, tranquility," 1510s, from calm (adj.) + -ness.
Entries linking to calmness
calm adj.
late 14c., of the sea, "windless, without motion or agitation;" of a wind, "light, gentle," perhaps via Old French calme "tranquility, quiet," or directly from Old Italian calma "quiet, fair weather," which probably is 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). The spelling was influenced by Latin calere "to be hot." The figurative application to social or mental conditions, "free from agitation or passion," is from 1560s.
-ness
word-forming element denoting action, quality, or state, attached to an adjective or past participle to form an abstract noun, from Old English -nes(s), from Proto-Germanic *in-assu- (cognates: Old Saxon -nissi, Middle Dutch -nisse, Dutch -nis, Old High German -nissa, German -nis, Gothic -inassus), from *-in-, originally belonging to the noun stem, + *-assu-, abstract noun suffix, probably from the same root as Latin -tudo (see -tude).