Look up umbral in Wiktionary, the free dictionary.
Umbral is derived from the Latin umbra, meaning "shadow". It is also the Spanish and Portuguese word for "threshold", and sometimes used as a surname in that language.
Umbral may also refer to:
- Umbral calculus, the surprising similarity between seemingly unrelated polynomial equations and certain shadowy techniques used to 'prove' them
- Umbral moonshine, a mysterious connection between Niemeier lattices and Ramanujan's mock theta functions
- Francisco Umbral (1932–2007), Spanish journalist, novelist, biographer and essayist
See also
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