adjective

1. good
2. of the most excellent sort; surpassing all others
3. most suitable, most desirable, most favorable, most profitable, etc.
4. being almost the whole; largest it took the best part of an hour

Etymology: ME best, betst < OE betst (akin to Goth batists) < ? IE base *bhad-, good > Sans bhadrá-ḥ, fortunate, good

adverb

1. well
2. in the most excellent manner; in the most suitable way
3. in the highest degree; to the greatest extent; most

noun

1. people of the highest worth, ability, or reputation among the best in his profession
2. the thing, condition, circumstance, action, etc. that is most excellent, most suitable, etc.
3. the most one can do; utmost to do one's best
4. advantage to get the best of an opponent
5. one's finest clothes

transitive verb