Dateline or deadline ?

Often, i see many people like to use dateline to represent end of a time line. But actually which is the correct one?

It should be deadline and not dateline. I don't know how everyone can come to this conclusion that dateline equivalent to end of a time frame?

According to dictionary.net deadline refers to the point in time at which something must be completed.

As for dateline it refers to a line at the beginning of a news article giving the date and place of origin of the news dispatch or mark with a date and place; "dateline a newspaper article" .

I find it weird why many of the notice board regardless in the schools or universities they use the word dateline to represent deadline.

Please do not learn the wrong thing. If you are not clear about the meaning then look into the dictionary.