1. Having no particular interest or concern; apathetic: indifferent to the sufferings of others.
2. Having no marked feeling for or against: She remained indifferent toward their proposal.
3. Not mattering one way or the other: It's indifferent to me which outfit you choose.
4. Characterized by a lack of partiality; unbiased: an indifferent judge.
5. Being neither too much nor too little; moderate.
6. Being neither good nor bad; mediocre: an indifferent performance. See synonyms at average.
7. Being neither right nor wrong.
8. Not active or involved; neutral: an indifferent chemical in a reaction.
9. Biology. Undifferentiated, as cells or tissue.

[Middle English, from Old French, from Latin indifferēns, indifferent- : in-, not; see in-¹ + differēns, different; see different.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.