No, it is a noun. Used with other nouns in terms such as deadline notice, it is a noun adjunct rather than an adjective.
A deadline can be changed, but a priority deadline cannot.
Deadlines is the plural of deadline
There are many verbs whose past participle may be used as adjectives, e.g. drawn, tired, passed. The word missed is the past tense and past participe and can be used as an adjective. Examples: Missed opportunities can haunt businessmen. (opportunities that were missed) A missed turn put us far out of our way. (a turn had been missed) The program had its first missed deadline. (the program had missed a deadline)
Deadlines is the plural of deadline
If the IRS receives your return or payment after the deadline date but it is postmarked on or before the deadline date, then it is considered to have been filed on time.
A fail; to meet a deadline is ridculous. If you have something to do and you have a deadline, you need to get it done
There was no fixed deadline.
Deadline - magazine - ended in 1995.
The Deadline was created on 2004-10-19.
Deadline Games ended in 2009.
The population of Deadline Games is 80.
Death on Deadline was created in 1987.