Origins
The word 'sharp' descends from Old English 'scearp' (sharp, cutting, pointed), from Proto-Germanic *skarpaz (sharp, cutting), from PIE *(s)ker- (to cut).βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ This PIE root is one of the most spectacularly productive in the entire Indo-European language family, generating a vast network of words across every branch. To trace the family of 'sharp' is to encounter a substantial portion of the English vocabulary.
The core meaning of *(s)ker- is 'to cut,' and its Germanic descendants radiate outward from this concept. 'Shear' (to cut, especially wool from sheep) comes directly from the root through Old English 'sceran.' 'Share' originally meant 'a cutting, a portion cut off' β your share of something is your cut. A 'ploughshare' is the cutting blade of a plough. 'Short' meant 'cut off, truncated' β something short has been cut down. 'Shirt' and 'skirt' are doublets β both mean 'a garment cut from cloth,' but 'shirt' entered through Old English 'scyrte' and 'skirt' through Old Norse 'skyrta,' the same Proto-Germanic word filtered through two different daughter languages. 'Score' originally meant 'a notch, a cut mark' β counts were kept by cutting notches in a stick, and every twentieth notch was cut deeper, which is why a 'score' came to mean twenty.
The Latin branch of *(s)ker- produced 'cortex' (bark β the outer layer 'cut off' from the tree, giving English 'cortex' and 'cortical'), 'corium' (leather, hide β the 'cut-off' skin), and 'curtus' (shortened, cut short β giving English 'curt' and 'curtail'). Greek 'keirein' (to cut, to shear) is a direct cognate. The s-mobile variant (the optional initial 's' that characterizes this root) is visible in the alternation between 'shear' (with s-) and 'curtail' (without s-).
Development
The semantic extensions of 'sharp' itself are remarkably wide. A sharp blade cuts physically. A sharp mind cuts through confusion. A sharp pain cuts into awareness. A sharp dresser has a 'cutting edge' in fashion. Sharp words cut emotionally. A sharp turn is an abrupt 'cut' in direction. In music, a sharp note is one that has been 'cut' upward from its natural pitch β raised by a semitone. The musical use dates from the sixteenth century.
The Germanic cognates are consistent: German 'scharf' (sharp, spicy β German uses the same word for a sharp blade and a spicy food, as does English to some extent: 'a sharp cheese'), Dutch 'scherp,' Swedish 'skarp,' Danish 'skarp,' Icelandic 'skarpur.' The Old Norse form was 'skarpr,' which influenced some Northern English dialects.
The compound 'sharpshooter' dates from the eighteenth century, originally a translation of German 'ScharfschΓΌtze' (sharp-shooter). 'Card sharp' (or 'card shark,' by folk etymology) refers to a person who is 'sharp' β keen, cunning β at cards. 'Sharper' was eighteenth-century slang for a swindler, someone whose wits were 'sharp' enough to cheat you.