Definition of preroll:
(n) :
(Internet, advertising, countable) An advertisement that plays before the main content.
(n) :
A joint which has been preprepared by a cannabis vendor or dispensary.
(n) :
(film, uncountable) A period of time during which the camera rolls but before the action begins.
(v) :
To roll something in advance.
(v) :
To make or show a preroll.