1. [mid-17C–19C] a simpleton, a victim.
2. [mid-17C–early 19C] a prostitute’s customer; thus cully-catching, picking up customers.
3. attrib. use of sense 2.
4. [late 17C–19C] a fop, a dandy.
5. [late 17C–1910s] a man, a fellow, a companion; often a term of address.
see rumper n. (1)
see under dark adj.