1830, of seas, "running in short, irregular, broken waves," from chop (v.2) + -y (2). Earlier in this sense was chopping (1630s).
Entries linking to choppy
chop v.2
"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 "engage in sophistical argument" is recorded from 1570s. Related: Chopped; chopping.
-y 2
adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy). Adjectives such as hugy, vasty are artificial words that exist for the sake of poetical metrics.