dicky vs backseat

dicky and backseat both are nouns.

Word	Noun	Adjective	Verb	Adverb
dicky	Yes	Yes	No	No
backseat	Yes	No	No	No

As nouns, backseat is a hypernym of dicky; that is, backseat is a word with a broader meaning than dicky:

dicky: a small third seat in the back of an old-fashioned two-seater
backseat: a seat at the back of a vehicle (especially the seat at the back of an automobile)

dicky (noun)	backseat (noun)
a man's detachable insert (usually starched) to simulate the front of a shirt	a seat at the back of a vehicle (especially the seat at the back of an automobile)
a small third seat in the back of an old-fashioned two-seater	a secondary or inferior position or status

dicky (adjective)	backseat (adjective)
(British informal) faulty