- A cylinder of wood, plastic, cardboard, or other material on which wire, thread, or string is wound. (noun)
- The amount of wire, thread, or string wound on such a cylinder. (noun)
- Something similar to such a cylinder in shape or function. (noun)
- A reel for magnetic tape. (noun)
- To wind or be wound on or off a spool. (verb-transitive)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.