oater means A movie or television show about cowboy or frontier life; a western movie. Lexicurio rates it Sui generis — a strength score of 91 out of 100.
oater is pronounced /ˈoʊ.tɚ/.
Etymology
From oat + -er (“Variety -er”). First use appears c. 1945-50, alluding to the fodder for horses, which are common in the movies.
noun
- A movie or television show about cowboy or frontier life; a western movie.“In recent years the western or horse opera, known in the trade as the "oater," has come to be recognized as an art form just as formal as the ballet or the symphony. […] To prove his contention that all this is so, Life Photographer John Florea took these unusual pictures during the filming of Yellow Sky. This is a $1,450,000 western with big-name stars […] and technical talent from 20th Century's”