chuckle (n.)

"a sly, suppressed laugh," 1754, from chuckle (v.).

chuckle (v.)

1590s, "to laugh loudly," frequentative of Middle English chukken "make a clucking noise" (late 14c.), of imitative origin. Meaning shifted to "laugh in a suppressed or covert way, express inward satisfaction by subdued laughter" by 1803. Related: Chuckled; chuckling.