electric chair vs death chair

electric chair and death chair both are nouns.

Word	Noun	Adjective	Verb	Adverb
electric chair	Yes	No	No	No
death chair	Yes	No	No	No

As nouns, electric chair and death chair are synonyms defined as:

electric chair and death chair: an instrument of execution by electrocution; resembles an ordinary seat for one person

Other synonyms of electric chair include chair, hot seat.

electric chair (noun)	death chair (noun)
an instrument of execution by electrocution; resembles an ordinary seat for one person	an instrument of execution by electrocution; resembles an ordinary seat for one person