convolution

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

• noun A form or part that is folded or coiled.
• noun One of the convex folds of the surface of the brain.

from The Century Dictionary.

• noun The act of rolling. or winding together, or of winding one part or thing on another; the motion or process of winding in and out.
• noun The state of being rolled upon itself, or rolled or wound together.
• noun A turn or winding; a fold; a gyration; an anfractuosity; a whorl: as, the convolutions of a vine; the convolutions of the intestines.
• noun In anatomy, specifically, one of the gyri, gyres, or anfractuosities of the brain, especially of the cerebrum. See cuts under brain and corpus.
• noun In mathematics, such a connection between the relations of any asyzygetic system that each is applied alternately in the aggregate of the remaining relations.

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

• noun The act of rolling anything upon itself, or one thing upon another; a winding motion.
• noun The state of being rolled upon itself, or rolled or doubled together; a tortuous or sinuous winding or fold, as of something rolled or folded upon itself.
• noun (Anat.) An irregular, tortuous folding of an organ or part.

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

• noun Something that is folded or twisted.
• noun Any of the folds on the surface of the brain.
• noun The shape of something rotating; a vortex.
• noun mathematics A form of moving average.
• noun computing A function which maps a tuple of sequences into a sequence of tuples.

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

• noun a convex fold or elevation in the surface of the brain
• noun the action of coiling or twisting or winding together
• noun the shape of something rotating rapidly