from The American Heritage® Dictionary of the English Language, 4th Edition
- n. One of two or more atoms having the same atomic number but different mass numbers.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- v. To define or demonstrate an isotopy of (one map with another).
- n. Any of two or more forms of an element where the atoms have the same number of protons, but a different number of neutrons within their nuclei. As a consequence, atoms for the same isotope will have the same atomic number but a different mass number (atomic weight).
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. one of two or more atoms with the same atomic number but with different numbers of neutrons
iso- + Greek topos, place (so called because the isotopes of a chemical element occupy the same position in the periodic table of elements).(American Heritage® Dictionary of the English Language, Fourth Edition)
Coined in 1914 by British chemist Frederick Soddy from Ancient Greek ἴσος (ísos, "equal; same") and τόπος (tópos, "place"), because the different isotopes of a chemical element always occupy the same position in the periodic table of elements. Compare the synonymous Icelandic word samsæta. (Wiktionary)