- a movie, television show, etc., about the frontier days of the U.S. West; western; horse opera.
Origin of oater
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Word Origin and History for oater
Western film, "horse opera," 1946, from oat, as the typical food of horses.
Online Etymology Dictionary, © 2010 Douglas Harper