Sibling adjectives are listed in this post. Each word below can often be found in front of the noun sibling in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing SIBLING.
adult, elder, eldest
female, full, male
new, next, old
older, oldest, only
other, younger, youngest
Hope this word list had the adjective used with sibling you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.
Annoying
annoying