Skill is Norse, and the sk- proves it: the native English line would have softened that cluster to sh-. English took it from Old Norse skil, "distinction, discernment, the ability to make out," in the early 1100s.
The meaning has moved a long way. The earliest English senses — knowledge, divine wisdom, power of discernment, sound judgment, that which is reasonable — are all obsolete now, and they cluster around telling things apart rather than doing things well. That fits the Norse root, which relates to a verb meaning "to separate, to discern," from an Indo-European root meaning "to cut." Practical ability and cleverness is recorded by the early 1200s and eventually took the word over entirely. Swedish still has skäl for "reason," and Danish skjel for a boundary.
skill (n.) early 12c., "knowledge, divine wisdom;" late 12c., "power of discernment, sound judgment; that which is reasonable," senses all now obsolete, from Old Norse skil "distinction, ability to make out, discernment, adjustment," which is related to skilja (v.) "to separate; discern, understand," from Proto-Germanic *skaljo- "divide, separate" (source also of Swedish skäl "reason," Danish skjel "a separation, boundary, limit," Middle Low German schillen "to differ," Middle Low German, Middle Dutch schele "separation, discrimination;" from PIE root *skel- (1) "to cut"). The sense of "practical knowledge and ability, cleverness" is recorded by early 13c. also from early 12c.
skill came in through Old Norse, and its spelling follows that family's conventions.
What gives it away on the page
| sk- | Native sc- had already softened to sh-, so a hard sk- came from somewhere else.sky, skin, skirt, skill, skull |
Old Norse in the spelling guide · guess another word's family