nope · particle, noun1
Representing no pronounced with the mouth snapped closed at the end. Luick instead claims it represents a realisation of no with final [ʔ], with a purported reduction of /p/ to [ʔ] before syllabic liquids providing a model for the spelling of [ʔ] as -pe, but it is more parsimonious to assume that the -pe directly represents attested realisations with [p̚]. Therefore no + -p. Compare yep/yup.
nope · noun2
Probably a rebracketing of an ope (see 1823 quote), from alp (“bullfinch”).
nope · noun, verb3
Nope · proper noun4
From a Wampanoag name for the island (or perhaps just for Gay Head, as 1841 cite).
Etymology from Wiktionary, CC BY-SA 4.0.