capper
[noun]
Synonyms: decoy, blind, bonnet, booster, shill, shillaber, stick

[TahlilGaran] English Synonym Dictionary ▲

capper noun. ['kapǝ] ME.
[from CAP noun¹ or verb¹ + -ER¹.]
1. A cap-maker. obsolete exc. Hist. ME.

2. A person who or thing which provides or forms a cap. L16.

3. An accomplice, esp. a confederate in a gambling game. slang (chiefly US). M18.

4. A person or thing that outdoes all rivals; something surprising or puzzling. dial. L18.

[TahlilGaran] English Dictionary ▲