4-letter words that end in on
- poon — any of several East Indian trees of the genus Calophyllum, that yield a light, hard wood used for masts, spars, etc.
- pron — Slang. pornography, especially on the Internet: When his girlfriend borrowed his computer, she found all the pr0n he'd been downloading.
- rmon — 1. (networking) remote monitoring. 2. Remote Monitor.
- roon — a shred or strip of cloth
- sion — a canton in SW Switzerland. 2021 sq. mi. (5235 sq. km). Capital: Sion.
- soon — within a short period after this or that time, event, etc.: We shall know soon after he calls.
- toon — (sometimes initial capital letter) a character in an animated cartoon.
- tron — 1. (project) The Real-Time Operating System Nucleus. 2. (language, programming, testing, tool) (TRace ON) A command used when debugging programs written in early line-numbered BASIC that contained GOTO and GOSUB statements. When the TRON command had been executed, the program ran with a window open indicating the line number being executed at that instant. The TROFF (an abbreviation for "TRace OFF") command turned the tracing off.
- udon — thick, white Japanese noodles made from wheat flour, often served in soup.
- upon — to, toward, or at an elevated place on or in: They went up the stairs. The cat is up the tree.
- woon — (obsolete) dwelling; wone.
- xeon — Pentium II Xeon
- yron — Archaic spelling of iron.
- zeon — The hot water added to the chalice by the priest during the Byzantine Eucharist to commemorate the water that flowed from the crucified Christ's side when pierced by the spear.
- zion — a hill in Jerusalem, on which the Temple was built (used to symbolize the city itself, especially as a religious or spiritual center).
- zoon — any of the individuals of a compound organism.