n.1. in many theories of memory, an attribute of the representational units (such as nodes or logogens) that varies from weaker to stronger, with more strongly activated representations competing to control processing. 2. the process of alerting an organ or body system for action, particularly arousal of one organ or system by another. An example is the pituitary gland’s release of hormones that activate the ovaries and testes for puberty. —activatevb.—activationaladj.