Deadline adjectives are listed in this post. Each word below can often be found in front of the noun deadline in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing DEADLINE.
certain, day, extended, final
firm, first, hard, hour
important, imposed, impossible, month
new, original, short, specific
statutory, strict, tight, week
Hope this word list had the adjective used with deadline you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.