Green’s Dictionary of Slang

sharp adj.

[fig. use of SE sharp]

1. [late 17C+] cunning, on the lookout for oneself.

2. [18C+] intelligent, perceptive.

3. [1910s+] of a woman, attractive.

4. [1920s+] fashionable, good, admirable.

5. [1940s+] good (of quality).

6. [1940s+] used of a person who dresses well and with style, e.g. sharp dresser.

7. [1940s+] (S.Afr.) good (of health).

8. [1950s] (US drugs) intoxicated by a given drug.

9. [1960s] (S.Afr.) promiscuous.

In compounds

sharping-omee (n.) (also sharpy) [omee n.]

[mid-19C] a policeman.

In phrases

not the sharpest tool in the shed

see under tool n.1

sharp as a harp (adj.)

[1940s] (Aus.) extra-conscientious.

sharp as a mosquito’s peter (adj.) (also sharp as a rat turd) [pun on SE sharp + mosquito pron. ‘moskeeter’ for assonance + peter n.4 ]

[1970s+] (US black) very smartly and fashionably dressed.

sharp up (v.) (also sharpen up)

[1930s+] (US) to dress up smartly.

you’re so sharp you’ll cut yourself

[20C+] a mocking phr. directed at someone who seems to think themselves exceptionally clever, well-informed etc..