[f. COOP v.1 + -ER.] One who coops or confines. (With quot. cf. COOP v.1 2 c.)
1889. Farmer, Americanisms, 168/2. To coop voters is to collect them as it were in a coop or cage, so as to be sure of their services on election day. Liquor dealers are the usual ‘coopers’ for obvious reasons.
