It forms all or part of: anatomy; atom; contemplate; contemplation; diatom; dichotomy; -ectomy; entomolite; entomology; entomophagous; epitome; phlebotomy; temple (n.1) "building for worship;" tmesis; tome; -tomy; tonsorial; tonsure.
It is the hypothetical source of/evidence for its existence is provided by: Greek temnein "to cut," tomos "volume, section of a book," originally "a section, piece cut off;" Old Church Slavonic tina "to cleave, split;" Middle Irish tamnaim "I cut off," Welsh tam "morsel."
"pertaining to atoms," 1670s as a philosophical term (see atomistic); scientific sense dates from 1811, from atom + -ic. Atomic number is from 1821; atomic mass is from 1848. Atomic energy first recorded 1906 in modern sense (as intra-atomic energy from 1903).
March, 1903, was an historic date for chemistry. It is, also, as we shall show, a date to which, in all probability, the men of the future will often refer as the veritable beginning of the larger powers and energies that they will control. It was in March, 1903, that Curie and Laborde announced the heat-emitting power of radium. [Robert Kennedy Duncan, "The New Knowledge," 1906]
Atomic bomb first recorded 1914 in writings of H.G. Wells ("The World Set Free"), who thought of it as a bomb "that would continue to explode indefinitely."
When you can drop just one atomic bomb and wipe out Paris or Berlin, war will have become monstrous and impossible. [S. Strunsky, Yale Review, January 1917]
Atomic Age is from 1945. Atomical "concerned with atoms," also "very minute," is from 1640s. Atomic clock is from 1938.
word-forming element denoting the presence of a carbonyl group or an oxygen atom linking two other atoms; from oxygen.
mid-15c., "a derived word or form, a word formed immediately or remotely from another or a root," from derivative (adj.). General sense of "that which is derived or deduced from another" is from 1590s. Mathematical sense, "a derivative function," is from 1670s. In chemistry, "compound that can be made from a parent compound by replacement of one atom with another atom or group of atoms," by 1855.