1.Definition: (comparative of `little' usually used with mass nouns) a quantifier meaning not as great in amount or degree

"Of less importance", "Less time to spend with the family", "A shower uses less water", "Less than three years old"

2.Definition: (nonstandard in some uses but often idiomatic with measure phrases) fewer

"Less than three weeks", "No less than 50 people attended", "In 25 words or less"

3.Definition: (usually preceded by `no') lower in quality

"No less than perfect"