n (biology) A single-stranded nucleic acid molecule required for the Wikipedia:DNA_replication | initiation of replication of a DNA molecule.
n A small charge that burns furiously when given sufficient electrical current (w:blasting cap|Explosive primer) or when struck with force (w:Percussion cap|percussion caps) that ignites the main combustion|combustable substances in explosives or ammunition.
n A layer of paint designed to underlay a topcoat, used to enhance the adhesion and durability of the topcoat and help in protection of the surface.