How Well Do You Know English Slang?
also top notch, 1848, from top (n.1) + notch (n.). Figurative of the "highest point" of something, but the exact mechanical image is uncertain.
Superior; of the highest quality; top-drawer: She's a top-notch racquetball player
[1900+; fr notch as representing position, rank, etc; found as a noun phrase, ''the highest degree of excellence,'' by 1833]