To observe (a day or event) with ceremonies of respect, festivity, or rejoicing. See Synonyms at observe. To perform (a religious ceremony): celebrate Mass. To extol or praise: a sonnet that celebrates love. To make widely known; display: "a determination on the author's part to celebrate . . . the offenses of another\u201d ( William H. Pritchard). To observe an occasion with appropriate ceremony or festivity. To perform a religious ceremony. To engage in festivities: went out and celebrated after the victory.