swum (sw?m)v.Past participle of swim.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.swum (sw?m) vb the past participle of swimCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014swim (sw?m) v. swam, swum, swim?ming, n. v.i. 1. to move in water by using the limbs, fins, tail, etc. 2. to float on the surface of water or some other liquid. 3. to move, rest, or be suspended in air as if swimming in water. 4. to move, glide, or go smoothly over a surface. 5. to be immersed or flooded with a liquid: eyes swimming with tears. 6. to be dizzy or giddy; seem to whirl: My head began to swim. v.t. 7. to move along in or cross (a body of water) by swimming. 8. to perform (a particular stroke) in swimming. 9. to cause to swim or float. n. 10. an act, instance, or period of swimming. 11. a motion as of swimming. Idioms: in the swim, alert to or actively engaged in current affairs, social activities, etc. [before 900; Middle English swimmen, Old English swimman, c. Old Saxon, Old High German swimman, Old Norse svimma] swim?mer, n. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.