be cocksure of (oneself)

To be completely certain of oneself or one's actions, to the point of overconfidence. You seem pretty cocksure of yourself—do you really know how to handle that machine?

Common Names:

Name	Pronounced	Usage
Gualterio	-	Spanish (Rare)
Volodislavu	-	Medieval Slavic
Lore (1)	LO-rə	German
Eliphelet	i-LIF-ə-let (English), ee-LIF-ə-let (English)	Biblical
Akamu	-	Hawaiian
Verginius	-	Ancient Roman