Word for word

Meaning

A precise following of another's words, i.e. verbatim, either in spoken repetition of those words or in a close study of a text.

Origin

The 'close study' meaning of the expression does back to at least 1385 when Chaucer used it in The Legend of Dido, a poem from Legend of Good Women:

I could folwe [follow] word for word Virgile.