org-agenda-deadline-leaders

org-agenda-deadline-leaders is a variable defined in `org-agenda.el'.
Its value is

("Deadline:  " "In %3d d.: " "%2d d. ago: ")

Documentation:
Text preceding deadline items in the agenda view.
This is a list with three strings. The first applies when the item has its
deadline on the current day. The second applies when the deadline is in the
future, the third one when it is in the past. The strings may contain %d
to capture the number of days.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.4 of Emacs.