Deadline or dateline....

Okay...this has been a mild form of frustation for me for a while......coz...I've always been under the impression that when something was suppose to be done by a certain time...it was called a deadline......but other people say...dateline......so here it is.......fresh from Wiktionary and Merriam Webster Online.....

Wiktionary:

deadline (plural deadlines)

1. A date on or before which something must be completed
   
   Merriam-Webster Online:
   
   dead·line
   Pronunciation: -"lIn
   Function: noun
   1 : a line drawn within or around a prison that a prisoner passes at the risk of being shot
   2 a : a date or time before which something must be done b : the time after which copy is not accepted for a particular issue of a publication
   - on deadline or under deadline : with the requirement of meeting a deadline on deadline>
   
   date·line
   Pronunciation: 'dAt-"lIn
   Function: noun
   1 : a line in a written document or a printed publication giving the date and place of composition or issue
   2 usually date line : INTERNATIONAL DATE LINE
   - dateline transitive verb

So there is it folks! Read 'em and weep. I rest my case.