aitio-, -aitio +

A descriptive term for reactions and movements caused by an external agent, a stimulus, or some force.

1. A tale devised to explain the origin of a religious observance.
2. The most general Greek term for a cause or a responsibility, used by Aristotle; especially, in reference to any one of the four kinds of answer it is legitimate to give in response to any "Why . . . ?" question.
3. Sometimes used for a myth that explains an origin, particularly how an object or custom came into existence.

1. A change in direction or bending caused by external forces.
2. The curvature of part of a plant stimulated by a widely spread or a scattered stimulus.

A reference to growth patterns and other phenomena imposed by the environment.

A reference to any movement that comes from an external stimulus.

Any tropism (movement, response) resulting from an exogenous (external) stimulus.