sharp

1 sharp /ˈʃɑɚp/ adjective
sharper; sharpest
1 sharp
/ˈʃɑɚp/
adjective
sharper; sharpest
Britannica Dictionary definition of SHARP
[also more sharp; most sharp]
1 
: having a thin edge that is able to cut things or a fine point that is able to make a hole in things — opposite blunt, dull; see also razor-sharp
2 
a  : sudden and quick
b  : involving a sudden change in direction
3 
a  : clear and easy to see
b  : very noticeable
4 
: having or showing a quick ability to notice and understand things
5 
: very sudden and severe
6 
: critical or harsh
8 
of cheese : having a strong odor and flavor
10 
disapproving : clever in a bad or dishonest way
11 
: ending in a point or edge
12 
informal : stylish or fashionable
13 
music
a  : higher than the true pitch
b  : higher than a specified note by a semitone — compare 1flat 10, 1natural 8

keep a sharp eye on

: to watch (someone or something) carefully

— sharpness

noun [noncount]
2 sharp /ˈʃɑɚp/ adverb
2 sharp
/ˈʃɑɚp/
adverb
Britannica Dictionary definition of SHARP
1 
: exactly — used to refer to an exact time
2 
: above the correct musical pitch — compare 3flat 4

look sharp

informal
: to act quickly : hurry
3 sharp /ˈʃɑɚp/ noun
plural sharps
3 sharp
/ˈʃɑɚp/
noun
plural sharps
Britannica Dictionary definition of SHARP
[count]
: a musical note that is one semitone higher than a specified note
also : a written symbol ♯ that is placed before a note to show that it should be played a semitone higher — compare 2flat 3, 2natural 2