/ak"teuh viz'euhm/ , n.
1. the doctrine or practice of vigorous action or involvement as a means of achieving political or other goals, sometimes by demonstrations, protests, etc.
2. Philos.
a. a theory that the essence of reality is pure activity, esp. spiritual activity, or process.
b. a theory that the relationship between the mind and the objects of perception depends upon the action of the mind.
[ 1905-10; Aktivismus. See ACTIVE, -ISM ]