(Excessively) detailed or specific; fastidious, fussy, nit-picky. / (poker slang) Of a poker player: playing in an overly cautious and reactive manner.

(obsolete, rare) Shining; elegant, spruce.

(originally US, colloquial, also attributively) The core or essence of something; the gist.

(chemistry) Any salt or ester of nitric acid.

To treat, or react, with nitric acid or a nitrate

(organic chemistry) The compound glyceryl-tri-nitrate or 1,2,3 tri-nitrooxy propane; the ester of glycerol with nitric acid; prepared by the careful addition of a mixture of nitric and sulphuric acids to glycerol with constant stirring and cooling; it is a thick, pale yellow liquid, that is highly explosive on concussion or on exposure to sudden heat; it is used in medicine as a vasodilator, and as an explosive in the form of dynamite which is safe to handle.

(informal) A scatterbrained or stupid person.

(figuratively) To correct insignificant mistakes or find fault in unimportant details. / (archaic, literally) To pick nits (lice eggs) from someone’s hair.

(inorganic chemistry) A non-flammable gas (N₂O) commonly used in surgery and dentistry for its anaesthetic and analgesic effects.

(inorganic chemistry) A transparent, colourless to pale yellow, fuming corrosive liquid, HNO₃; a highly reactive oxidizing agent used in the production of fertilizers, explosives, and rocket fuels and in a wide variety of industrial processes; once called aqua fortis.