sweet (adj.)

Old English swete "pleasing to the senses, mind or feelings; having a pleasant disposition," from Proto-Germanic *swotja- (source also of Old Saxon swoti, Old Frisian swet, Swedish söt, Danish sød, Middle Dutch soete, Dutch zoet, Old High German swuozi, German süß), from PIE root *swād- "sweet, pleasant" (Sanskrit svadus "sweet;" Greek hedys "sweet, pleasant, agreeable," hedone "pleasure;" Latin suavis "pleasant" (not especially of taste), suadere "to advise," properly "to make something pleasant to"). Words for "sweet" in Indo-European languages typically are used for other sense as well and in general for "pleasing."

Then come kiss me, sweet-and-twenty!
Youth's a stuff will not endure.
["Twelfth Night"]

Also "being in a sound or wholesome state" (mid-13c.), and, of water, "fresh, not salt" (late Old English). As an intensifier from 1958. Sweet in bed (c. 1300) was the equivalent of modern "good in bed." To be sweet on someone is first recorded 1690s. Sweet sixteen first recorded 1767. Sweet dreams as a parting to one going to sleep is attested from 1897, short for sweet dreams to you, etc. Sweet-and-sour in cookery is from 1723 and not originally of oriental food. Sweet nothings "sentimental trivialities" is from 1900. Sweet spot is from 1976, first in reference to tennis rackets. Sweet corn is from 1640s.

sweet (n.)

c. 1300, "something sweet to the taste," also "beloved one," from sweet (adj.); the specific meaning "candy drop" is 1851 (earlier sweetie, 1721). Meaning "one who is dear to another" is from 14c. Old English swete (n.) meant "sweetness."

Definitions of sweet
sweet (adj.)
having or denoting the characteristic taste of sugar;
sweet (adj.)
having a sweet nature befitting an angel or cherub;
a sweet disposition
Synonyms: angelic / angelical / cherubic / seraphic
sweet (adj.)
pleasing to the ear;
Synonyms: dulcet / honeyed / mellifluous / mellisonant
sweet (adj.)
pleasing to the senses;
the sweet face of a child
the sweet song of the lark
sweet (adj.)
pleasing to the mind or feeling;
sweet revenge
Synonyms: gratifying
sweet (adj.)
having a natural fragrance;
Synonyms: odoriferous / odorous / perfumed / scented / sweet-scented / sweet-smelling
sweet (adj.)
(used of wines) having a high residual sugar content;
sweet dessert wines
sweet (adj.)
not soured or preserved;
sweet milk
Synonyms: fresh / unfermented
sweet (adj.)
with sweetening added;
Synonyms: sugared / sweetened / sweet-flavored
sweet (adj.)
not containing or composed of salt water;
Synonyms: fresh
sweet (n.)
a dish served as the last course of a meal;
Synonyms: dessert / afters
sweet (n.)
a food rich in sugar;
Synonyms: confection
sweet (n.)
the taste experience when sugar dissolves in the mouth;
Synonyms: sweetness / sugariness
sweet (n.)
the property of tasting as if it contains sugar;
Synonyms: sweetness
sweet (adv.)
in an affectionate or loving manner (`sweet' is sometimes a poetic or informal variant of `sweetly'); "how sweet the moonlight sleeps upon this bank"- Shakespeare;
talking sweet to each other
Synonyms: sweetly
Sweet (n.)
English phonetician; one of the founders of modern phonetics (1845-1912);
Synonyms: Henry Sweet