nitty-gritty

noun

1. the essential substance or details of a matter; basics; crux: Let’s skip the chitchat and get down to the nitty-gritty.

adjective

2. fundamental, detailed, or probing: nitty-gritty questions.
3. direct and practical: nitty-gritty advice; a nitty-gritty system.

noun

1. the nitty-gritty informal the basic facts of a matter, situation, etc; the core

n.“basic facts,” 1961, knitty-gritty, American English, said to have been chiefly used by black jazz musicians, perhaps ultimately from nit and grits “finely ground corn.” As an adjective from 1966.