To cut away a small portion of an edge of a stack of sheets or a book block, either to reduce a set of sheets to a desired size or to cut away signature folds. See Cutting and Trimming. It is also used as a noun to refer to the trim size.
In graphics, trim means to cut away a portion of a line, arc, or circle.
In video production, trim means to select specific frames for inclusion in a master tape.
Also a term to describe a shorter version of preventative maintenance on a printer. It is also a term used to cut the tractor feed portion from continuous forms.