Meanings
nounx unit (plural x units)
plural x units
- A unit of length (symbol xu) approximately equal to 0.1 picometres, used to quote the wavelength of X-rays and gamma rays.
Synonyms: Siegbahn unit
Synonyms & antonyms
nounA unit of length (symbol xu) approximately equal to 0.1 picometres, used to quote the wavelength of X-rays and gamma rays.
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Also see
Origin
After X-ray (x signifying the unknown).
Full word history & related roots →Cite this entry
APA
x unit. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/x%20unit
MLA
“x unit.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/x%20unit. Accessed November 3, 2026.
Chicago
WatkinsX Dictionary, s.v. “x unit,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/x%20unit.
Source: x unit on Wiktionary, CC BY-SA 4.0.