To interact socially, engross or hold attention, draw into conversation, attract, please, fascinate, or win over someone.

To interact antagonistically, enter into conflict with an enemy, or enter into battle.

Interact contractually, arrange employment or use, guarantee or promise, bind through legal or moral obligation, pledge or put at risk.

Interact mechanically, mesh or interlock (especially a clutch), and come into gear (engineering).

(intransitive) To enter into (an activity), to participate (construed with in).

(transitive, obsolete) To entangle.