Wiktionary (0.00 / 0 votes) Rate this definition: pellet (Noun). Usually a small, compressed, symmetrical and hard chunk of matter. Ex: Wood pellet, ore pellet, etc. pellet (Noun). A lead projectile used as ammunition in rifled air guns.pellet (Noun). Compressed byproduct of digestion regurgitated by owls.iktionary (0.00 / 0 votes) Rate this definition: pellet (Noun). Usually a small, compressed, symmetrical and hard chunk of matter. Ex: Wood pellet, ore pellet, etc. pellet (Noun). A lead projectile used as ammunition in rifled air guns.