tumbler pigeon vs tumbler

tumbler pigeon and tumbler both are nouns.

Word	Noun	Adjective	Verb	Adverb
tumbler pigeon	Yes	No	No	No
tumbler	Yes	No	No	No

As nouns, tumbler pigeon and tumbler are synonyms defined as:

tumbler pigeon and tumbler: pigeon that executes backward somersaults in flight or on the ground

Other synonyms of tumbler pigeon include roller.

tumbler pigeon (noun)	tumbler (noun)
pigeon that executes backward somersaults in flight or on the ground	pigeon that executes backward somersaults in flight or on the ground
	a glass with a flat bottom but no handle or stem; originally had a round bottom
	a movable obstruction in a lock that must be adjusted to a given position (as by a key) before the bolt can be thrown
	a gymnast who performs rolls and somersaults and twists etc.