Why is a diode called unidirectional?

A diode is unidirectional because of the diode only conduct in forwardbias .As you know the diode have two terminal cathode and anode . and when the positive terminal of battery connected to the p-side and other terminal connected to the other terminal of diode then diode is called forward biased . and when it connection is just opposite then it become in reverse biased .

so we can finally say that the diode is unidirectional