snicker · noun, verb1
US variant of the British snigger, possibly of onomatopoeic origin, similar to Dutch snikken (“to gasp; sob”). The noun is first recorded 1836, from the verb. Compare also Scottish smicker (“to smile or laugh in a sniggering or leery way, smirk”). More at smicker.
snicker · noun2
Etymology from Wiktionary, CC BY-SA 4.0.