col·lar (k?l??r)n.1. a. The part of a garment that encircles the neck, especially when raised or folded.b. See clerical collar.2. A tight-fitting necklace.3. a. A restraining or identifying band of leather, metal, or plastic put around the neck of an animal.b. The cushioned part of a harness that presses against the shoulders of a draft animal.4. Biology An encircling structure or bandlike marking, as around the neck of an animal, suggestive of a collar.5. Any of various ringlike devices used to limit, guide, or secure a machine part.6. Slang An arrest, as of a criminal.tr.v. col·lared, col·lar·ing, col·lars 1. To furnish with a collar.2. Slang a. To seize or detain.b. To arrest (a criminal, for example).[Middle English coler, from Old French colier, from Latin coll?re, from collum, neck; see kwel- in Indo-European roots.]col?lared adj.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.