Meaning of “best” - Learner’s Dictionary

best

adverb uk us /best/
DEGREE

A1 superlative of well adverb : most, or more than any other:

Which of the songs did you like best?
WAY

B1 in the most suitable or satisfactory way:

I sleep best with the windows open.

(Definition of “best adverb” from the Cambridge Learner’s Dictionary © Cambridge University Press)