fight (v.) Look up fight at Dictionary.com
Old English feohtan "to fight" (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. To fight back "resist" is recorded from 1890.
fight (n.) Look up fight at Dictionary.com
Old English feohte, gefeoht "a fight;" see fight (v.). Compare Old Frisian fiucht, Old Saxon fehta, Dutch gevecht, Old High German gifeht, German Gefecht.