From PIE *oktow — cognate with Latin 'octo' and Greek 'okto.' The silent 'gh' preserves a once-pronounced guttural.
The cardinal number following seven and preceding nine; the cube of two.
From Old English eahta, from Proto-Germanic *ahtō, from PIE *oḱtṓw (eight). This numeral is strikingly uniform across Indo-European: Latin octō, Greek oktṓ, Sanskrit aṣṭā́(u), Lithuanian aštuonì, Old Irish ocht, Old Church Slavonic osmĭ, Tocharian B okt. Some linguists have analyzed the PIE form as a dual number, meaning 'two fours' (*oḱtṓw < *h₃eḱt-h₃ow), suggesting that eight was conceptualized as two groups of four in the earliest counting systems