Real Dictionary

sharp
adjective: A sharp bend or turn is one that changes direction suddenly.
adjective: A sharp point or edge is very thin and can cut through things very easily. A sharp knife, tool, or other object has a point or edge of this kind.
adjective: You can describe a shape or an object as sharp if part of it or one end of it comes to a point or forms an angle.

sharp in American English
suitable for use in cutting or piercing; having a very thin edge or fine point; keen
adjective: having a thin cutting edge or a fine point; well-adapted for cutting or piercing
adverb: keenly or acutely
intransitive verb: to sound above the true pitch
noun: something sharp
transitive verb: to raise in pitch, esp. by one chromatic half step

sharp in British English
adjective: having a keen edge suitable for cutting
noun: Cecil (James). 1859–1924, British musician, best known for collecting, editing, and publishing English folk songs