Late 16th century; earliest use found in Nicholas Breton (?1555–c1626), poet. Probably from nod + -cock, hypocoristic suffix. Compare slightly earlier nodgecock and slightly later niddicock.
Definition of nodcock in US English:
nodcock
nounˈnɒdkɒk
Regional archaic
A fool; a simpleton.
Origin
Late 16th century; earliest use found in Nicholas Breton (?1555–c1626), poet. Probably from nod + -cock, hypocoristic suffix. Compare slightly earlier nodgecock and slightly later niddicock.