The member of parliament elected by his peers in the Commons to act as their representative and moderator of their debates. The first speaker, Peter de la Mare, was appointed during the Good Parliament of 1376. During the reign of Henry V, Thomas Chaucer, the son of Geoffrey Chaucer, was speaker. In the 14c, once the Commons had reached a decision, it was the speaker who would deliver it to the Lords. In the French of the time it was the speaker qui avoit les paroles pur les Communes d'Engleterre en cest Parlement = who has the words of the Commons of this parliament.
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.