1. tightly or immovably wedged in.
  2. Dentistry. noting a tooth so confined in its socket as to be incapable of normal eruption.
  3. driven together; tightly packed.
  4. densely populated or crowded; overcrowded: an impacted school district.

Origin of impacted

1675–85; obsolete impact adj. (< Latin impāctus past participle of impingere to fasten, cause to collide, strike, equivalent to im- im-1 + pag-, variant stem of pangere to drive in, plant firmly + -tus past participle suffix) + -ed2; see impinge
Related formsnon·im·pact·ed, adjectiveun·im·pact·ed, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for unimpacted


  1. (of a tooth) unable to erupt, esp because of being wedged against another tooth below the gum
  2. (of a fracture) having the jagged broken ends wedged into each other
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

unimpacted in Medicine


  1. Wedged together at the broken ends. Used of a fractured bone.
  2. Placed in the alveolus in a manner prohibiting eruption into a normal position. Used of a tooth.
  3. Packed in or wedged in such a manner so as to fill or block an organ or a passage.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.