Word: betterest
Part of speech: Verb
Syllables: be
tter
est
Definition: Alternative form of better; thoroughly or completely; fully; often used as a combining form; 
Morphemes:
Affix: better
Language: en
PoS: Adjective
Meaning: Alternative form of well; in a good or proper or satisfactory manner or to a high standard (`good' is a nonstandard dialectal variant for `well')
Affix: -est
Language: en
PoS: Suffix
Meaning: Used to form the superlative of adjectives and adverbs.