sharp

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Having a thin edge or a fine point suitable for or capable of cutting or piercing.
• adjective Having clear form and detail.
• adjective Terminating in an edge or a point.
• adjective Clearly and distinctly set forth.
• adjective Abrupt or acute.
• adjective Intellectually penetrating; astute.
• adjective Marked by keenness and accuracy of perception.
• adjective Crafty or deceitful, as in business dealings.
• adjective Vigilant; alert.
• adjective Briskly or keenly cold and cutting.
• adjective Harsh or biting in tone or character.
• adjective Fierce or impetuous; violent.
• adjective Intense; severe.
• adjective Sudden and shrill.
• adjective Sudden and brilliant or dazzling.
• adjective Strongly affecting the senses of smell and taste.
• adjective Composed of hard angular particles.
• adjective Raised in pitch by a semitone.
• adjective Being above the proper pitch.
• adjective Having the key signature in sharps.
• adjective Informal Attractive or stylish.
• adverb In a sharp manner.
• adverb Punctually; exactly.
• adverb Music Above the true or proper pitch.
• noun A sign (♯) used to indicate that a note is to be raised by a semitone.
• noun A note that is raised a semitone.
• noun A slender sewing needle with a very fine point.
• noun An expert.
• noun A shrewd cheater; a sharper.
• intransitive verb To raise in pitch by a semitone.
• intransitive verb To play or sing above the proper pitch.

from The Century Dictionary.

• To sharpen; make keen or acute.
• In music, to elevate (a tone); specifically, to apply a sharp to (a note or staff-degree)—that is, to elevate it a half-step. Also sharpen.
• To indulge in sharp practices; play the sharper; cheat.
• In music, to sing or play above the true pitch. Also sharpen.
• noun The tone given by such a key, or a tone in unison with such a tone: the D sharp next above middle C has (at French pitch) about 308 vibrations per second.
• noun The staff-degree assigned to such a key or tone, being the same as that for D, but with a sharp upon it either in the signature or as an accidental.
• noun A note placed on such a degree and indicating such a key or tone.
• noun The key-note of the minor key of six sharps (D sharp minor).
• noun In the fixed system of solmization, the sharp of the second tone of the scale, technically named ri.
• noun The tone given by such a key, or a tone in unison with such a tone: the G sharp next above middle C has (at French pitch) about 411 vibrations per second.
• noun The staff-degree assigned to such a key or tone, being the same as that for G, but with a ♮ upon it either in the signature or as an accidental.
• noun A note placed on such a degree and indicating such a key or tone.