lightest

of comparatively little physical weight or density;
(used of color) having a relatively small amount of coloring agent;
of the military or industry; using (or being) relatively small or light arms or equipment;
not great in degree or quantity or number;
psychologically light; especially free from sadness or troubles;
characterized by or emitting light;
(used of vowels or syllables) pronounced with little or no stress;
easily assimilated in the alimentary canal; not rich or heavily seasoned;
(used of soil) loose and large-grained in consistency;
(of sound or color) free from anything that dulls or dims;
moving easily and quickly; nimble;
demanding little effort; not burdensome;
of little intensity or power or force;
(physics, chemistry) not having atomic weight greater than average;
weak and likely to lose consciousness;
very thin and insubstantial;
marked by temperance in indulgence;
less than the correct or legal or full amount often deliberately so;
having little importance;
intended primarily as entertainment; not serious or profound;
silly or trivial;
designed for ease of movement or to carry little weight;
having relatively few calories;
(of sleep) easily disturbed;
casual and unrestrained in sexual behavior;

lightest is a valid Scrabble (US) TWL word

lightest is a valid Scrabble Word in Merriam-Webster MW Dictionary

lightest is a valid Scrabble Word in International Collins CSW Dictionary

lightest is a valid Words With Friends word