trig (adj.) Look up trig at Dictionary.com
"smart, trim," c. 1200, from Old Norse tryggr "firm, trusty, true," from Proto-Germanic *treuwaz- (see true (adj.)). A Scottish and northern word only until 19c. Related: Trigness.
trig (n.) Look up trig at Dictionary.com
1895 as a shortening of trigonometry.