Twin adjectives are listed in this post. Each word below can often be found in front of the noun twin in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing TWIN.
conjoined, dark, dead
elder, evil, first
fraternal, identical, lost
older, other, own
second, siamese, younger
Hope this word list had the adjective used with twin you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.
Please add more adjectives to make this list more complete: