isomorphism (n.)

"similarity of form," 1822, in John George Children's translation from French of Berzelius's "The Use of the Blow-pipe in Chemical Analysis," from French l'isomorphisme, from German Isomorphismus (1819), coined by German chemist Eilhard Mitscherlich (1794-1863) from Greek isos "equal, identical" (see iso-) + morphe "form, appearance," a word of uncertain etymology.

Mr. Children has, very properly in our estimation, wholly omitted the formulae, translating them into plain English in notes at the bottom of the page; we wish he had exerted the same discretionary judgment with respect to the isomorphisms and left them out likewise. [from a review of Children's book in The Quarterly Review of Science, Literature, and the Arts, vol. xiii, 1822]