In the name of Allah, the Most Gracious, the Most Merciful,
Deadline refers to a particular time or date which something should be completed. 
Example: "The deadline is tomorrow and you are telling me this now?"
It is not to be confused with dateline, which is a line of text, usually at the beginning of an article or a news report, which shows the date and origin of an article.
Allah knows best.
 Taken from definition of deadline from Oxford Dictionaries Online.