• (RP) IPA: /ˈnɪtiː/, /ˈnɪtɪ/
• (America) IPA: /ˈnɪti/, /-ɾi/

From nit + -y.

The origin of the noun sense (“dope fiend, druggie”) is unknown, but could refer to a person who is under the influence of drugs to the extent that he or she is careless about personal hygiene and unkempt. Compare the verb nit ("to be a nitty").

nitty (comparative nittier, superlative nittiest)

1. (archaic, also, figuratively) Full of nits.

   Synonyms: lousy

   • 1601, Ben Jonson, Poetaster or The Arraignment: […], London: […] [R. Bradock] for M[atthew] L[ownes] […], published 1602, →OCLC ↗, Act III ↗:

     Tuc[ca]. […] Can thy Author doe it impudently enough? / Hiſt[rio]. O, I warrant you, Captaine: and ſpitefully inough too; he ha's one of the moſt ouerflowing villanous wits, in Rome. He will ſlander any man that breathes; If he diſguſt him. / Tucca. I'le know the poor, egregious, nitty Raſcall; and he haue ſuch commendable Qualities, I'le cheriſh him: […]

2. (chiefly, Britain, slang) Foolish, inane.

   Synonyms: dumb, idiotic, Thesaurus:stupid, Thesaurus:foolish

nitty (plural nitties)

1. (AAVE, MLE, slang) A dope fiend, a druggie.

   Synonyms: Thesaurus:addict

Probably from nitty(-gritty).

nitty (comparative nittier, superlative nittiest)

1. (Excessively) detailed or specific; fastidious, fussy, nit-picky.

   Synonyms: Thesaurus:fastidious

2. (poker slang) Of a poker player: playing in an overly cautious and reactive manner.

A clipping of nitid (“bright, lustrous, shining”), or directly derived from Latin nitidus, from niteō ("to glitter, shine; to look beautiful or bright") (from Proto-Indo-European *ney-) + idus ("suffix meaning ‘tending to’").

nitty

1. (obsolete, rare) Shining; elegant, spruce.