preroll

• pre-roll

pre- +‎ roll

preroll (countable and uncountable, plural prerolls)

1. (film, uncountable) A period of time during which the camera rolls but before the action begins.
2. (Internet, advertising, countable) An advertisement that plays before the main content.
   • 2009 July 27, Brooks Barnes, “Lab Watches Web Surfers to See Which Ads Work”, in New York Times‎:

     Are ads that play before video clips, known as prerolls, more effective when paired with banner ads?

• (advertisement before main content): intromercial

preroll (third-person singular simple present prerolls, present participle prerolling, simple past and past participle prerolled)

1. To roll something in advance.
2. To make or show a preroll.

• proller