Late 18th century; earliest use found in George Ellis (1753–1815), writer. In allusion to the practice among many Scots of tracing clan lineage back to remote degrees.
Definition of Scotch cousin in US English:
Scotch cousin
noun
A distant relative.
Origin
Late 18th century; earliest use found in George Ellis (1753–1815), writer. In allusion to the practice among many Scots of tracing clan lineage back to remote degrees.