Definition of most:

part of speech: adverb

In the greatest or highest degree; for the greatest part: at most, or at the most, within the furthest limits; the utmost extent: to make the most of, to derive the greatest benefit or advantage from.

part of speech: noun

The greatest number, part, or quantity; the utmost value or extent- when used as a noun, the noun is usually understood.

part of speech: adjective

Superl. degree of much; consisting of the greatest number or quantity.