An anonymous user suggested that this word would be derived from nappi(“button”) + -ttaa(“causative clitic”), stating that: "Etymology was purely speculative and had no evidence to support it". I reverted this edit to "onomatopoeic", because:
if "onomatopoeic" appears as speculative proposition, derivation from nappi is even more so, as there's no logic why the word signifying "to tap" would be derived from a word that signifies "button"
the causative word derived from nappi is napittaa(“to button, button up”) < nappi + -ttaa
