adj. phr. 1. Very neatly and stylishly dressed That new boy always looks sharp as a tack in class. 2. Very intelligent; smart; quick-witted. Tom is sharp as a tack; he got 100 on every test.
SHARP AS A TACK
Meaning of SHARP AS A TACK in English
American idioms English vocabulary. Английский словарь американских идиом. 2012