soft (adj.)

Old English softe, earlier sefte, "gentle, mild-natured; easeful, comfortable, calm, undisturbed; luxurious," from West Germanic *samfti, from Proto-Germanic *samftijaz "level, even, smooth, gentle, soft" (source also of Old Saxon safti, Old High German semfti, German sanft; and from a variant form with -ch- for -f-, Middle Dutch sachte, Dutch zacht, German sacht), from root *som- "fitting, agreeable."

From c. 1200 of material things, "not stiff, not coarse, fine; yielding to weight." From late 14c. of wind, rain, etc. Of sounds, "quiet, not loud," from early 13c. Of words, "mild, restrained; courteous" mid-14c. From late 14c. as "indulgent," also "physically feeble; easily overcome, lacking manly courage." From 1755 of water ("relatively free from mineral salts"), from 1789 of coal. Meaning "foolish, simple, silly" is attested from 1620s; earlier "easily moved or swayed; soft-hearted, sympathetic; docile" (early 13c.). In reference to drinks, "non-alcoholic" from 1880. As an adverb, Old English softe "gently;" late 13c. as "quietly." As an interjection from 1540s.

Soft landing is from 1958 and the U.S. space program. Adjective soft-core (in reference to pornography) is from 1966 (see hardcore). Soft rock as a music style is attested from 1969. Soft sell is from 1955. Soft-shoe as a dancing style is attested from 1927. Soft-boiled is from 1757 of eggs; of persons, ideas, etc., 1930 (compare half-baked). Soft-focus (adj.) of camera shots is from 1917. The softer sex "women collectively" is from 1640s.

Definitions of soft
soft (adj.)
yielding readily to pressure or weight;
soft (adj.)
compassionate and kind; conciliatory;
he was soft on his children
soft (adj.)
(of sound) relatively low in volume;
soft voices
soft music
soft (adj.)
easily hurt;
soft hands
Synonyms: delicate
soft (adj.)
produced with vibration of the vocal cords;
Synonyms: voiced / sonant
soft (adj.)
not protected against attack (especially by nuclear weapons);
soft targets
soft (adj.)
(of light) transmitted from a broad light source or reflected;
Synonyms: diffuse / diffused
soft (adj.)
(of speech sounds); produced with the back of the tongue raised toward the hard palate; characterized by a hissing or hushing sound (as `s' and `sh');
soft (adj.)
(of a commodity or market or currency) falling or likely to fall in value;
the market for computers is soft
soft (adj.)
using evidence not readily amenable to experimental verification or refutation;
the soft sciences
soft data
soft (adj.)
tolerant or lenient;
too soft on the children
they are soft on crime
Synonyms: indulgent / lenient
soft (adj.)
soft and mild; not harsh or stern or severe;
Synonyms: gentle
soft (adj.)
having little impact;
a soft (or light) tapping at the window
Synonyms: easy / gentle
soft (adj.)
out of condition; not strong or robust; incapable of exertion or endurance;
he was too soft for the army
Synonyms: flabby / flaccid
soft (adj.)
willing to negotiate and compromise;
soft (adj.)
not burdensome or demanding; borne or done easily and without hardship;
a soft job
Synonyms: cushy / easygoing
soft (adj.)
mild and pleasant;
a soft breeze
Synonyms: balmy / mild
soft (adj.)
not brilliant or glaring;
the moon cast soft shadows
soft pastel colors
Synonyms: subdued
soft (adj.)
(used chiefly as a direction or description in music) soft; in a quiet, subdued tone;
Synonyms: piano
soft (adv.)
in a relaxed manner; or without hardship;
Synonyms: easy