(1) any substance, usually of hypothalamic origin, capable of accelerating the rate of secretion of a given hormone by the anterior pituitary gland; (2) factors required in the termination phase of either RNA biosynthesis or protein biosynthesis. SYN: termination factor. (3) colloquial shortened form for the HMG-CoA reductase inhibitors used as antihyperlipidemic agents, whose generic names end with the suffix statin. SYN: statins. SYN: liberins, releasing hormone.