The Collaborative International Dictionary
left field \left` field"\, leftfield \left`field"\n. (Baseball) the part of the outfield on the catcher's or batter's left.
Syn: left.
Wiktionary
n. 1 (context baseball English) The 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 (context baseball English) The defensive position in the outfield to the left. 3 (context idiomatic English) An unexpected, bizarre, or unwatched source (especially in the phrases '''out of left field''' and '''from left field'''). 4 (context idiomatic English) An 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''')
WordNet
n. the piece of ground in the outfield on the catcher's left [syn: left]
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)
Usage examples of "left field".
The question had come from left field and wasn't connected to anything that had been going on.