fro

The word 'fro' is a fossilized fragment of language, surviving almost exclusively in the phrase 'to and fro'. It originated as a shortening of the Middle English 'froon', which derived from the Old Norse preposition 'frá', meaning 'from'. This Norse term is cognate with the English preposition 'from', both tracing back to a common Germanic root. In the rhythmic pairing 'to and fro', the word 'fro' has been preserved for centuries to denote motion away from a starting point, while its standalone use has otherwise vanished from modern English.

This is a simplex word, a clipped form of the earlier adverb 'froon', which itself came from Old Norse 'frá', meaning 'from'.