—v.t. 1. to observe (a day) or commemorate (an event) with ceremonies or festivities: to celebrate Christmas; to celebrate the success of a new play. 2. to make known publicly; proclaim: The newspaper celebrated the end of the war in red headlines. 3. to praise widely or to present to widespread and favorable public notice, as through newspapers or novels: a novel celebrating the joys of marriage; the countryside celebrated in the novels of Hardy. 4. to perform with appropriate rites and ceremonies; solemnize: to celebrate a marriage.
—v.i. 1. to observe a day or commemorate an event with ceremonies or festivities.
2. to perform a religious ceremony, esp. Mass or the Lord's Supper.
3. to have or participate in a party, drinking spree, or uninhibited good time: You look like you were up celebrating all night.