noun. A termination of Greek origin, existing in many English words derived from the Greek or formed on Greek analogy, denoting an agent (one who does or has to do with a thing), and corresponding usually to nouns in -er, with which in some cases they interchange.

"The frequent _ist das_ signifies merely "das ist," or it is the echo of the oft-heard question, "Was ist das?" and is uttered without the tone of interrogation."