mediation vs umpirage

mediation and umpirage both are nouns.

Word	Noun	Adjective	Verb	Adverb
mediation	Yes	No	No	No
umpirage	Yes	No	No	No

As nouns, umpirage is a hyponym of mediation; that is, umpirage is a word with a more specific, narrower meaning than mediation:

mediation: a negotiation to resolve differences that is conducted by some impartial party
umpirage: mediation by an umpire

Other hyponyms of mediation include arbitration, conciliation.

mediation (noun)	umpirage (noun)
the act of intervening for the purpose of bringing about a settlement	the act of umpiring
a negotiation to resolve differences that is conducted by some impartial party	mediation by an umpire