Obsolete is a verb, but it is a poor choice. A better choice would be obsolesce, as in: "LESS.js will obsolesce CSS" "Obsolete" is the correct word becaus

Obsolete is a verb, but it is a poor choice. A better choice would be obsolesce, as in: "LESS.js will obsolesce CSS" "Obsolete" is the correct word because it's a transitive verb (eg, [subject] obsoletes [object]), while obsolesce is an intransitive verb (eg, [subject] obsolesces).