1550s, "act or process by which organisms absorb their proper food into their systems and build it into living tissue," from Old French nutrition (14c.) and directly from Latin nutritionem (nominative nutritio) "a nourishing," noun of action from past-participle stem of nutrire "to nourish, suckle, feed," from PIE *nu-tri-, suffixed form (with feminine agent suffix) of *(s)nau- "to swim, flow, let flow," hence "to suckle," extended form of root *sna- "to swim." Meaning "that which nourishes, nutriment" is from c. 1600. Related: Nutritional.

"one whose profession is advising on matters of food and nutrition and their effect on health," 1926, from nutrition + -ist.

"containing or contributing nourishment," 1660s, from Latin nutricius "that which nourishes, nurses," from nutrix (genitive nutricis) "a nurse," from nutrire "to nourish, suckle, feed," from PIE *nu-tri-, suffixed form (with feminine agent suffix) of *(s)nau- "to swim, flow, let flow," hence "to suckle," extended form of root *sna- "to swim." An earlier word was nutrimental (late 14c.). Related: Nutritiously.

late 14c., "concerned with or pertaining to the function of nourishing," from Old French nutritif and directly from Medieval Latin nutritivus "nourishing," from nutrit-, past-participle stem of Latin nutrire "to nourish, suckle, feed," from PIE *nu-tri-, suffixed form (with feminine agent suffix) of *(s)nau- "to swim, flow, let flow," hence "to suckle," extended form of root *sna- "to swim." Meaning "having the property of nourishing, nutritious" is from early 15c.

"crazy, not right in the head," 1846, from earlier colloquial or slang be nuts on "be very fond of" (1785), which is possibly from nuts (plural noun) "any source of pleasure or delight" (1610s), from nut (q.v.). Nuts as a special treat or favorite foodstuff led to other figurative phrases, now obsolete. The "crazy" sense probably has been influenced by metaphoric application of nut to "head" (1846, as in to be off one's nut "be insane," 1860). Also compare nutty. Nuts as a derisive retort is attested from 1931.

Connection with the slang "testicles" sense has tended to nudge the word toward taboo territory. "On the N.B.C. network, it is forbidden to call any character a nut; you have to call him a screwball." [New Yorker, Dec. 23, 1950] "Please eliminate the expression 'nuts to you' from Egbert's speech." [Request from the Hays Office regarding the script of "The Bank Dick," 1940] This desire for avoidance probably accounts for the euphemism nerts (c. 1925).

c. 1200, nute-scale, "hard shell which forms the covering of the kernel of a nut;" see nut (n.) + shell (n.). Figurative use with reference to "great condensation" (1570s, as in in a nutshell) supposedly originally is a reference to a tiny copy of the "Iliad," mentioned by Pliny (and in English from late 14c.), which could fit into the shell of a nut.

late 15c., "one who gathers nuts," from nut + -er (1). Meaning "crazy person" is British slang, by 1958, from nut + -er (3). Nuttery "mental hospital" is attested in slang from 1931; earlier it meant "place for storing nuts" (1881).

"action of gathering nuts," 1723, verbal noun from nut (v.) "to gather nuts" (c. 1600), from nut (n.).

early 15c., "nut-like," from nut (n.) + -y (2); from 1660s as "abounding in nuts." Sense of "having the flavor of nuts" is by 1828. Slang meaning "crazy" is by 1898 (see nuts); earlier colloquial sense was "amorous, in love (with)," 1821. [Byron, in a slangy passage in "Don Juan" (1823) uses it of a beggar's doxy; a footnote defines it as "conjointly, amorous and fascinating."] Related: Nuttiness.

early 15c., "to bring the nose to the ground," back-formation from noselyng "face-downward, on the nose, in a prostrate position" (c. 1400), frequentative of nose (v.). The meaning "burrow with the nose, thrust the nose into" is attested from 1520s; that of "lie snug" is from 1590s, influenced by nestle, or by nursle, frequentative of nurse (v.). Related: Nuzzled; nuzzling.