centerfield vs piece of ground

centerfield and piece of ground both are nouns.

Word	Noun	Adjective	Verb	Adverb
centerfield	Yes	No	No	No
piece of ground	Yes	No	No	No

As nouns, piece of ground is a hypernym of centerfield; that is, piece of ground is a word with a broader meaning than centerfield:

centerfield: the piece of ground in the outfield directly ahead of the catcher
piece of ground: an extended area of land

Other hypernyms of centerfield include parcel, parcel of land, piece of land, tract.

centerfield (noun)	piece of ground (noun)
the fielding position of the player on a baseball team who is expected to field balls in the central third of the outfield	an extended area of land
the piece of ground in the outfield directly ahead of the catcher