What is the X in X-mas?
"jaws, sides of the face," c.1500, perhaps a variant of chaps (n.2) in the same sense, which is of unknown origin.
"to cut with a quick blow," mid-14c., of uncertain origin, perhaps from Old North French choper (Old French coper "to cut, cut off," 12c., Modern French couper), from Vulgar Latin *cuppare "to behead," from a root meaning "head," but influenced in Old French by couper "to strike." Related: Chopped; chopping.
"shift quickly," 1530s, earlier "to bargain" (early 15c.), ultimately from Old English ceapian "to bargain" (see cheap); here with a sense of "changing back and forth," probably from common expressions such as to chop and change "barter." To chop logic is recorded from 1570s. Related: Chopped; chopping.
"act of chopping," mid-14c., from chop (v.1). Meaning "piece cut off" is mid-15c.; specifically "slice of meat" from mid-17c. Sense of "a blow, strike" is from 1550s.
[senses related to skill fr notion of a jazz musician's lips, chops, the essential for technique in ''blowing'' the instrument]
[1823+; fr Hindi, ''seal'']