throne vs mercy seat

throne and mercy seat both are nouns.

Word	Noun	Adjective	Verb	Adverb
throne	Yes	No	Yes	No
mercy seat	Yes	No	No	No

As nouns, mercy seat is a hyponym of throne; that is, mercy seat is a word with a more specific, narrower meaning than throne:

Other hyponyms of throne include bishop's throne, cathedra, musnud, peacock-throne.

throne (noun)	mercy seat (noun)
the position and power of an exalted person (a sovereign or bishop) who is entitled to sit in a chair of state on ceremonial occasions	the golden covering of the ark of the covenant
the chair of state for a monarch, bishop, etc.	the throne of God
a plumbing fixture for defecation and urination

throne (verb)	mercy seat (verb)
put a monarch on the throne
sit on the throne as a ruler