The unclear verse “Three Quarks for Muster Mark!”, introduced by James Joyce (1882–1941) to his novel entitled Finnegans Wake (first published in 1939), was a literary source for the English word quark denoting ‘an elementary particle with a fractional electric charge that is part of a proton, neutron or other interacting elementary particle’. The American physicist Murray Gell-Mann, winner of the Nobel Prize in Physics in 1969, was the first researcher to introduce the English word quark into scientific terminology as early as in 1964. After accepting his hypothesis of quarks in the world science, most physicists adopted the English term quark as standard in the physical terminology of most international languages (e.g. French quark, German Quark, Italian quark, Polish kwark, Portugal quark, Russian кварк, Spanish cuark, Turkish kuark, Ukrainian кварк ‘an elementary particle’) and it quickly became a widely recognized internationalism. It is not commonly known that Joyce’s verse facetiously imitated loud cries of German dairy women: Drei Mark für muster Quark! (literally “Three Marks for an excellent curd!”). In other words, E. quark ‘an elementary particle’ is motivated by the German term Quark m. ‘weiser Käse / curd, white cheese’, metaphorically ‘trifle, nonsense, trash, worthless thing’, which – according to most German and Slavic etymologists – represents an obvious Slavic borrowing (especially a Polish or Lower Sorbian loanword), cf. Pol. twaróg, dial. kwaruk m. ‘curd, white cheese’ (< Proto-Slavic *tvarogъ m. ‘id.’). It is suggested that the specialized term kwark represents the so called back-borrowing in the Polish language.