left field vs left fielder

left field and left fielder both are nouns.

Word	Noun	Adjective	Verb	Adverb
left field	Yes	No	No	No
left fielder	Yes	No	No	No

left field (noun)	left fielder (noun)
the fielding position of the player on a baseball team who is expected to field balls in the left third of the outfield (looking from home plate)	the person who plays left field
the piece of ground in the outfield on the catcher's left