ч. т. д. – English translation

QED (Q.E.D. or QED is an initialism of the Latin phrase "quod erat demonstrandum", literally meaning "what was to be shown". Traditionally, the abbreviation is placed at the end of a mathematical proof or philosophical argument in print publications to indicate that the proof or the argument is complete, and hence is used with the meaning "thus it has been demonstrated".)

Russian thesaurus