D defs.my
Entry 2 senses Webster, 1913

Rustler

/rŭs'-lẽr/ · Rus·tler · IPA /rˈʌslər/
01 n. One who, or that which, rustles.
  1. 1.
    One who, or that which, rustles.
  2. 2.
    A bovine animal that can care for itself in any circumstances; also, an alert, energetic, driving person.[Slang, Western U.S.]