biradical

As a noun biradical

is (chemistry) any molecule having two independent radical centres.

As a letter x is

the twenty-fourth letter of the.

As a symbol x is

voiceless velar fricative.

As a noun biradical

is (chemistry) any molecule having two independent radical centres.

As an adjective undefined is

lacking a definition or value.

In chemistry terms the difference between diradical and biradical

is that diradical is a divalent radical while biradical is any molecule having two independent radical centres.