shrug

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To raise (the shoulders), especially as a gesture of doubt, disdain, or indifference.
• intransitive verb To raise the shoulders, especially as a gesture of doubt, disdain, or indifference.
• noun An expressive gesture of raising the shoulders.
• noun A very short woman's jacket or sweater, having long or short sleeves and usually worn open down the front.

from The Century Dictionary.

• noun An expressive drawing up of the shoulders: a characteristic manner of expressing doubt, indifference, discontent, contempt, etc., or, rarely, relief or resignation.
• noun A hitching up of the clothes.
• To shrink or shiver with or as with cold; draw up the limbs in a nervous shiver.
• To raise or draw up and contract the shoulders with a sudden, nervous movement: an expression usually of doubt, indifference, discontent, dislike, contempt, etc.
• Reflexively, to draw up the shoulders of in a shrug.
• To draw up with a sudden, nervous movement; contract in a shrug.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To draw up or contract (the shoulders), especially by way of expressing doubt, indifference, dislike, dread, or the like.
• intransitive verb To raise or draw up the shoulders, as in expressing doubt, indifference, dislike, dread, or the like.
• noun A gesture consisting of drawing up the shoulders, -- a motion usually expressing doubt, indifference, or dislike; -- it is sometimes accompanied by a slight turning of the hands outward or upward. Such a gesture may be made, as in answering "who knows" to a question, suggesting utter ignorance of an answer and a disinclination to pursue the topic further.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A lifting of the shoulders to signal indifference.
• noun A cropped, cardigan-like garment with short or long sleeves, typically knitted.
• verb intransitive To raise the shoulders to express a lack of knowledge or certainty.
• verb intransitive To raise the shoulders to express a lack of concern or worry.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb raise one's shoulders to indicate indifference or resignation
• noun a gesture involving the shoulders