fight (v.)youdaoicibaDictYouDict[fight 词源字典]
Old English feohtan "to combat, contend with weapons, strive; attack; gain by fighting, win" (intransitive; class III strong verb; past tense feaht, past participle fohten), from Proto-Germanic *fehtan (cognates: Old High German fehtan, German fechten, Middle Dutch and Dutch vechten, Old Frisian fiuhta "to fight"), from PIE *pek- (2) "to pluck out" (wool or hair), apparently with a notion of "pulling roughly" (cognates: Greek pekein "to comb, shear," pekos "fleece, wool;" Persian pashm "wool, down," Latin pectere "to comb," Sanskrit paksman- "eyebrows, hair").

Spelling substitution of -gh- for a "hard H" sound was a Middle English scribal habit, especially before -t-. In some late Old English examples, the middle consonant was represented by a yogh. Among provincial early Modern English spellings, Wright lists faight, fate, fecht, feeght, feight, feit, feyght, feyt, feort, foight.

From c. 1200 as "offer resistance, struggle;" also "to quarrel, wrangle, create a disturbance." From late 14c. as "be in conflict." Transitive use from 1690s. To fight for "contest on behalf of" is from early 14c. To fight back "resist" is recorded from 1890. Well figt þat wel fligt ("he fights well that flies fast") was a Middle English proverb.[fight etymology, fight origin, 英语词源]
repugnant (adj.)youdaoicibaDictYouDict
late 14c., "contrary, contradictory," from Old French repugnant "contradictory, opposing" or directly from Latin repugnantem (nominative repugnans), present participle of repugnare "to resist, fight back, oppose; disagree, be incompatible," from re- "back" (see re-) + pugnare "to fight" (see pugnacious). Meaning "distasteful, objectionable" is from 1777.