What do you call the language used during Shakespeare, Petrarch or Chaucer's time?

Question

I'm making a research paper on the evolution of language, from archaic to slang. I need ideas.. and really, what do you call the poetic language used by Shakespeare in his sonnets? I figured that I musn't use "archaic language" to refer to it. :D

Any help about how and why languages evolve will be greatly appreciated. Thanks in advance!! :D

Answer 1

Shakespeare wrote in early Modern English of his day.
Chaucer wrote in Middle English of his day.
Petrarch (and Dante) wrote in Middle Italian of their time.

Answer 2

The English language is broken down into 3 major areas:
Old English, Middle English, and Modern English. And within each of these are subsets.

Chaucer's English is Late Middle (or Late Medieval) English. Petrarch didn't write in English, but the English of his time would have been similar to Chaucer's.

Shakespeare's English is, believe it or not, Early Modern English.

The website below is pretty good.