Tough
Old English tōh, of Germanic origin; related to Dutch taai and German zäh .
wiktionary
From Middle English tough, towgh, tou, toȝ, from Old English tōh(“tough, tenacious, holding fast together; pliant; sticky, glutinous, clammy”), from Proto-West Germanic *tą̄h(ī), from Proto-Germanic *tanhuz(“fitting; clinging; tenacious; tough”), from Proto-Indo-European *denḱ-(“to bite”).
etymonline
tough (adj.)
Old English toh "strong and firm in texture, tenacious, sticky," from Proto-Germanic *tanhu- (source also of Middle Low German tege, Middle Dutch taey, Dutch taai, Old High German zach, German zäh), which Watkins suggests is from PIE *denk- "to bite," from the notion of "holding fast." See rough for spelling change.
From c. 1200 as "strong, powerful;" c. 1300 as "not tender or fragile;" early 14c. as "difficult to chew," also "hard to endure." Figurative sense of "steadfast" is mid-14c.; that of "hard to do, trying, laborious" is from 1610s. Verb tough it "endure the experience" is first recorded 1830, American English. Tough guy attested from 1901. Tough-minded first recorded 1907 in William James. Tough luck first recorded 1912; tough shit, dismissive retort to a complaint, is from 1946.
tough (n.)
"street ruffian," 1866, American English, from tough (adj.).
