Birthday adjectives are listed in this post. Each word below can often be found in front of the noun birthday in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing BIRTHDAY.
actual, annual, approaching, beautiful, belated, best, big, centennial, early, eighteenth, eighth, eightieth, eleventh
fifteenth, fifth, fiftieth, first, fortieth, fourteenth, fourth, good, great, happy, her, his, holiday
huge, hundredth, important, large, last, little, lovely, more, my, national, new, next, nice
nineteenth, ninetieth, ninth, official, old, other, own, perfect, real, recent, royal, same, second
seventeenth, seventh, seventieth, sixteenth, sixth, sixtieth, small, special, spiritual, surprise, tenth, third, thirteenth
thirtieth, traditional, true, twelfth, twentieth, twentyfirst, upcoming, wonderful
Hope this word list had the adjective used with birthday you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.