The context of a due date originated in journalism, probably from an earlier usage in printing, representing a guideline marked on a plate for a printing press (inside which all content should appear). According to the Oxford English Dictionary, early usage refers simply to lines that do not move, such as one used in angling; slightly later American usage includes a boundary around a prison which prisoners must not cross.
deadline (plural deadlines)
- A date on or before which something must be completed.
- I must make this deadline or my boss will kill me!
- (archaic) A guideline marked on a plate for a printing press.
- (archaic) A line which doesn't move.
- (archaic) A boundary around a prison.
The declension of this word is problematic. Joukahainen recommends nalle-type declension, presumably based on the spelling of the word:
On the other hand, nalle-declension does not fit with the pronunciation, which would rather indicate risti-type declension. It would probably be advisable to avoid using this word in written communication, and use Finnish synonyms instead.