cocky · adjective1
From cock (“male domestic chicken”) + -y (suffix forming adjectives with the sense of ‘having the quality of’).
cocky · noun2
From cock (“male domestic chicken”) + -y (diminutive suffix).
cocky · noun, verb3
The noun is derived from cock(atoo) + -y (diminutive suffix). The verb is derived from the noun.
Etymology from Wiktionary, CC BY-SA 4.0.