WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
a feeling of lack of concern
noun.
the trait of remaining calm and seeming not to care; a casual lack of concern
Word Usage
"Ignore it deliberately, as a kitten stalks away with feigned unconcern from a suddenly tedious cotton-reel, in the hope that, seen afresh from the other side of the room, it will turn once more into a mouse."