Did the space persons even have Tonka-tough steel to make those motors?
tough (n.)
"street ruffian," 1866, American English, from tough (adj.).
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tough (adj.)
Old English toh "strong and firm in texture, tenacious,
sticky," from Proto-Germanic *tanhu- (cognates: 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."
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.
...to
bite? Sticky? Shit, I hope they didn't use 'em!