Old English spelt, perhaps an early borrowing from Late Latin spelta "spelt" (c.400, noted as a foreign word), which is perhaps ultimately from PIE root *spel- "to split, to break off" (probably in reference to the splitting of its husks in threshing), which is related to the root of flint.
The word had little currency in English, and its history is discontinuous. Widespread in Romanic languages (cf. Italian spelta, Spanish espelta, Old French spelte, Modern French épeautre). The word also is widespread in Germanic (cf. Old High German spelta, German Spelt), and a Germanic language is perhaps the source of the Late Latin word.