less (Adjective) — (comparative of 'little' usually used with mass nouns) a quantifier meaning not as great in amount or degree. ex. "of less importance" ex. "less time to spend with the family" ex. "a shower uses less water" ex. "less than three years old"
less (Adjective) — (usually preceded by 'no') lower in quality. ex. "no less than perfect"
less (Adjective) — (nonstandard in some uses but often idiomatic with measure phrases) fewer. ex. "less than three weeks" ex. "no less than 50 people attended" ex. "in 25 words or less"
less (Adverb) — Used to form the comparative of some adjectives and adverbs. ex. "less expensive" ex. "less quickly" ex. "less interesting"
less (Adverb) — Comparative of little. ex. "she walks less than she should" ex. "he works less these days"
less (Preposition) — With subtraction of; not including.