— interactional , adj.
/in'teuhr ak"sheuhn/ , n.
1. reciprocal action, effect, or influence.
2. Physics.
a. the direct effect that one kind of particle has on another, in particular, in inducing the emission or absorption of one particle by another.
b. the mathematical expression that specifies the nature and strength of this effect.
[ 1825-35; INTER- + ACTION ]