Merry, Happy, Joyous, Cheerful, Glad. prevalent synonyms, to ensure they mean pertaining to thing, as well as all adjectives, which means they describe nouns. But only one of such describes the noun Christmas or the noun Birthday. Happy Christmas and Merry Birthday do not exist in North American English, even http://manuel99oc0.blogdal.com/6285797/teaching-vocabulary-to-learners-of-english-as-a-distant-language