A substitution.
Something added to fill a gap.
An intermediate result that must be stored temporarily during the course of a sparse matrix computation.
A temporary replacement for another, especially at a job.
A musical embellishment (usually percussion) that is added to connect musical phrases.
A product category that is used to complete a range or variety of a product line.
Something added to increase the size of something; padding or filler.
A question or puzzle in which one is expected to fill in a missing part of something.
A substitute; something that substitutes for another.
A substituendum; something to be substituted or replaced.