Meaning of -EST in English

-EST

1.

suffix forming the superlative of adjectives (widest; nicest; happiest) and adverbs (soonest).

Etymology: OE -ost-, -ust-, -ast- 2.

suffix (also -st) archaic forming the 2nd person sing. of verbs (canst; findest; gavest).

Etymology: OE -est, -ast, -st

Oxford English vocab.      Оксфордский английский словарь.