sleet (sl?t)n.1. Precipitation consisting of small ice pellets formed by the freezing of raindrops or of melted snowflakes.2. A mixture of rain and snow or hail.3. A thin icy coating that forms when rain or sleet freezes, as on trees or streets.intr.v. sleet·ed, sleet·ing, sleets To shower sleet.[Middle English slete, probably from Old English *sl?te; akin to German Schlosse, hail.]sleet?y 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.