Unidirectional - Unidirectional Unidirectional Unidirectional Unidirectional Unidirectional Unidirectional Unidirectional Unidirectional Unidirectional ! HAHA :)

The unidirectional flow of traffic on the highway made it easier for drivers to navigate.

No, "unidirectional" is not a noun. It is an adjective that describes something moving or operating in one direction.

An antonym of unidirectional (one direction) would be omnidirectional (all directions).

Yes it can be used as a unidirectional microphone if needed.