Early 19th century; earliest use found in Jane Austen (1775–1817), novelist. Variant or alteration of nuncheon, perhaps humorously after shine, moonshine; perhaps compare also slightly later shine.
Definition of noonshine in US English:
noonshine
nounˈnuːnʃʌɪn
historical
= nuncheon.
Origin
Early 19th century; earliest use found in Jane Austen (1775–1817), novelist. Variant or alteration of nuncheon, perhaps humorously after shine, moonshine; perhaps compare also slightly later shine.