Geoffrey Chaucer (c.1342-1400) and William Shakespeare (1564-1616)
are both credited with increasing English vocabulary. There is no proof
that either of them actually invented the words we find in their works.
All we can say for certain is that the words appeared for the first time
in their works; it is likely that many of these words were in common
use on the streets of London.
While Shakespeare is usually the first to come to mind when the
subject of contributions to the English language comes up, Chaucer
actually gets credit for having more words we know now appear in his
works first. Of course, since he had a two-century head start on Shakespeare, maybe it isn't a fair contest.
Chaucer gets the credit if you can:
check the galaxy called Milky Way
bear a corrosive test
observe an oriental Persian
foster a superlative rumour
clasp a dagger
be victorious
varnish a convertible
muse on femininity
amble the equator
preen, murmur, vomit, fart, strangle, commit, retain, oppress, create a mystery, or replenish material.