1. An extremely vulgar insult
2. Used to describe one who enjoys the eating of grass, mulch, dirt, and other objects commonly found in yards

See also: Spacemouth, Mountainmouth, Rotundamouth et al.
Ugh...Drew...you're such a yardmouth!

Hey, look at that yardmouth eating his grass and dirt...haha...yardmouth.
by Phat Phunk Drizzle November 21, 2005
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