exotic atom
Also found in: Dictionary, Wikipedia.
exotic atom
[ik¦säd·ik ′ad·əm] (atomic physics)
A system in which either the proton that forms the nucleus of a hydrogen atom is replaced by another particle (such as a muon, to form muonium, or a positron, to form positronium), one electron in an ordinary atom is replaced by another particle (such as a muon, pion, or antiproton), or both substitutions are made (as in antihydrogen).
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.