Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.

WORD ORIGIN

1896, translation of German X-strahl, from X, algebraic symbol for an unknown quantity, + Strahl (plural Strahlen) "beam, ray." Coined 1895 by German scientist Wilhelm Conrad Röntgen (1845-1923), who discovered them.

Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.