The term "bidirectional" may refer to:
- Anything that can move in two directions
- A roadway that carries traffic moving in opposite directions
- 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 (see also Push-pull train)
- Bi-directional text
- Duplex (telecommunications)
- Bidirectionalization
- Bi-directional railway signalling