loco

• POS: Adjective, Noun, Verb (transitive)
• HYPHEN: lo=co

CIDE DICTIONARY

loco, adv. [It.].

 A direction in written or printed music to return to the proper pitch after having played an octave higher.  [1913 Webster]

loco, n. [Sp. loco insane.].

•  A plant (Astragalus Hornii) growing in the Southwestern United States, which is said to poison horses and cattle, first making them insane. The name is also given vaguely to several other species of the same genus. Called also loco weed.  [1913 Webster]
•  Any one of various leguminous plants or weeds besides Astragalus, whose herbage is poisonous to cattle, as Spiesia Lambertii, syn. Oxytropis Lambertii.  [Webster 1913 Suppl.]

loco, v. t. 

 To poison with loco; to affect with the loco disease; hence (Colloq.), to render insane or mad.  W. D. Howells.  [Webster 1913 Suppl.]

loco, n. 

 A locomotive.  Kipling.  [Webster 1913 Suppl.]

loco, a. [Sp. loco insane.].

 Insane; crazy.  [PJC]

OXFORD DICTIONARY

loco, n. (pl. -os) colloq. a locomotive engine.

loco, adj. & n.
--adj. sl. crazy.
--n. (pl. -oes or -os) (in full loco-weed) a poisonous leguminous plant of the US causing brain disease in cattle eating it.

Etymology

Sp., = insane

THESAURUS

loco

abnormal, bereft of reason, brainsick, crackbrained, cracked, crazed, crazy, daft, deluded, demented, deprived of reason, deranged, disoriented, distraught, flighty, fruity, hallucinated, insane, irrational, lunatic, mad, maddened, maniac, manic, mazed, mental, mentally deficient, meshuggah, mindless, moon-struck, non compos, non compos mentis, not all there, not right, nuts, odd, of unsound mind, off, psycho, queer, reasonless, senseless, sick, stark-mad, stark-staring mad, strange, tetched, touched, unbalanced, unhinged, unsane, unsettled, unsound, wandering, witless