Bidirectional, a roadway that carries traffic moving in opposite directions
Bi-directional vehicle, a tram or train or any other vehicle that can be controlled from either end and can move forward or backward with equal ease without any need to be turned around
Bidirectional text, text containing text in both text directionalities
Duplex (telecommunications), communication in both directions
Bidirectionalization, a process in computer science
Bidirectional railway signalling; see Application of railway signals#Bidirectional signalling
Bidirectional learning/process refers to two way learning. In terms of socialization, the process helps both novices and experts learn from each other.