Know why cattywampus was trending last week?
1787, from Scottish, where apparently it survived as an alteration of Middle English glenten "gleam, flash, glisten" (mid-15c.), from a Scandinavian source (cf. Norwegian gletta "to look," dialectal Swedish glinta "to shine"), from Proto-Germanic *glent-, from PIE *ghel- "to shine, glitter, glow, be warm" (see glass). Reintroduced into literary English by Burns. Related: Glinted; glinting.
1540s (modern use from 1826), from glint (v.).