Meanings
- informalSynonym of ronto- (used before an official prefix existed). Symbol: x
From Nanotech to Xennotech [...] A one-kilogram hole has a radius of about 10⁻²⁷ meter.
2004 November, Seth Lloyd, Y. Jack Ng, “Black Hole Computers”, in Scientific American, page 562 more examples
The SI prefixes above are not the only extreme ones. Others such as xenno (x) (10⁻²⁷) and xenna (X) (10²⁷), or vendeko (v) (10⁻³³) and vendeka (V) (10³³) exist, and can help simplify the expression of extreme numbers.
1994, IPC Magazines, New Scientist, volume 144, page 81'Now we're talking xennobiology!' [...] a complex organism based on similar processes to the primitive ones they'd seen probably would be about a xennometre in size.
2002, Greg Egan, Schild's Ladder, Gollancz, published 2008, page 184Synonyms: ronto-
Synonyms & antonyms
prefixSynonym of ronto- (used before an official prefix existed). Symbol: x
Origin
- Ancient Greekἐννέα“nine”
- Englishxenno-
From Ancient Greek ἐννέα (ennéa, “nine”), for the ninth order of 10³; with the letter x added for the third term in a series running backwards through the alphabet (after zepto- and yocto-). The final o conforms to the final vowels of the SI series from micro- downwards.
More words from Ancient Greek
Full word history & related roots →Cite this entry
xenno-. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/xenno-
“xenno-.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/xenno-. Accessed November 4, 2026.
WatkinsX Dictionary, s.v. “xenno-,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/xenno-.
Source: xenno- on Wiktionary, CC BY-SA 4.0.