chill (n.)
Old English ciele, cele "cold, coolness, chill, frost," from Proto-Germanic *kal- "to be cold," from PIE root *gel- "cold" (see cold). According to OED, the word seems to have been obsolete after c.1400 (displaced by cold) and the modern use is a back-formation since c.1600 from the verb.
chill (v.)
late 14c., intransitive, "to feel cold, grow cold;" c.1400, transitive, "to make cold," from chill (n.). Related: Chilled; chilling; chillingly. Figurative use from late 14c. Meaning "hang out" first recorded 1985; from earlier chill out "relax" (1979).
Sheila E. sizzles in the new flick, Krush Groove, but some New York critics couldn't groove with it because many of the terms are unfamiliar to them. Examples: breakin' out (slang for leaving), chill (for cool down) and death (for something that's really good). ["Jet," Nov. 11, 1985]