gran·ule (gr?n?yo?ol)n.1. A small grain or pellet; a particle.2. Geology A rock or mineral fragment larger than a sand grain and smaller than a pebble, between 2 and 4 millimeters in diameter.3. Astronomy One of the small, transient, luminous markings in the photosphere of the sun.4. Biology A cellular or cytoplasmic particle, especially one that stains readily.[Late Latin gr?nulum, diminutive of Latin gr?num, grain; see gr??-no- in Indo-European roots.]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.granule (??rænju?l) n1. a small grain2. (Geological Science) geology a single rock fragment in gravel, smaller than a pebble but larger than a sand grain3. (Astronomy) astronomy another name for granulation5[C17: from Late Latin gr?nulum a small grain]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014gran?ule (?græn yul) n. 1. a little grain. 2. a small particle; pellet. [1645?55;