What linguistic feature defines the 'Gawain-Poet's' work, distinguishing it from the London dialect of Chaucer?

Correct answer: Use of the Northwest Midlands dialect

The Gawain-Poet wrote in a Northwest Midlands dialect, which is far more conservative than Chaucer's London dialect. It features a denser use of alliterative vocabulary rooted in the Old English tradition rather than French courtly convention.