1.NounThe part of a baseball field which is beyond the infield and to the left of a person standing on home plate and facing the pitcher.
2.NounThe defensive position in the outfield to the left.
3.NounAn unexpected, bizarre, or unwatched source (especially in the phrases out of left field and from left field).
"Some of her comments really came from left field. I have no idea what she was thinking."
4.NounAn unusual or unexpected position, or a viewpoint held by very few others in contrast to the majority viewpoint (especially in the phrases out in left field and way out in left field)