Webster’s Revised Unabridged Dictionary · 1913
Duffer
Duf′fer, n. 1. (Mining) See Shicer.
2. (Zoöl.) Any common domestic pigeon.
Duf′fer, n. One who duffs cattle, etc. [Australia]
Unluckily, cattle stealers are by no means so rare as would be desirable; they are locally known as duffers. Baden-Powell.