
A frame line is the unused space that separates two adjacent images, or film frames, on the release print of a motion picture. They can vary in width; a 35 mm film with a 1.85:1 hard matte has a frame line approximately 8 millimeters (0.3 inches) high, whereas both a full frame negative and the anamorphic format have very narrow frame lines, with ...
Found on
http://en.wikipedia.org/wiki/Frame_line

The small sliver of space between frames. This is where two shots are cut apart and joined.
Found on
https://www.encyclo.co.uk/local/21112

a horizontal line separating consecutive frames on a strip of film.
Found on
https://www.infoplease.com/dictionary/frame-line
No exact match found.