lightness

Etymology 1

From Middle English lightnes, lightnesse, from Old English līhtnes, lȳhtnys (“enlightening, illumination”), from Proto-West Germanic *liuhtinassī; equivalent to light (“to make bright, illuminate”, verb) + -ness (suffix forming nouns). Cognate with Old High German liuhtnissi (“illumination, enlightening”).

noun

1. (uncountable) the condition of being illuminated
2. (uncountable) the relative whiteness or transparency of a colour
3. (countable) The product of being illuminated.

Etymology 2

From Middle English lightnes, lightnesse,, from Old English *lēohtnes (“lightness”) (compare Old English lēohtmōdnes (“lightness”, literally “light-moodedness”), līhtingnes (“lightness, alleviation”)); equivalent to light (“not heavy”, adjective) + -ness (suffix forming nouns). Cognate with Middle Low German luchtnisse, lüchtnisse (“lightness, frivolity, joyfulness”).

noun

1. The state of having little (or less) weight, or little force.
   The unique chassis design is largely the secret of the lightness of the locomotive. 1960 January, “The Swindon Type "4" diesel-hydraulic units”, in Trains Illustrated, page 39
2. Agility of movement.
3. Freedom from worry.
   In the lightness of my heart I sang catches of songs as my horse gayly bore me along the well-remembered road. 1852, Mrs M.A. Thompson, “The Tutor's Daughter”, in Graham's American Monthly Magazine of Literature, Art, and Fashion, page 266
4. Levity, frivolity; inconsistency.
   Seneca […] accounts it a filthy lightness in men, every day to lay new foundations of their life, but who doth otherwise? , New York 2001, p.75