(rail transport, of an electric train) Able to run using two different voltages, depending on the voltage supplied to the particular railway line, whether by third rail direct current or overhead wires.

plural of Hodge dual

(law, taxation) A person who is a resident for tax purposes in two or more countries.

plural of dual resident

(electrical engineering) Able to operate on two different electrical frequencies. / (radio communications) Able to receive and operate on two different radio frequencies.

(education, psychology) Twice-exceptional.

(US, military) The requirement for an incoming nuclear attack to be confirmed by both satellite and radar before retaliatory action is taken.

(of a person, potentially offensive) Having mixed racial parentage or ancestry.

(grammar) A noun (or specific sense of a noun) that can only occur in the dual, and which lacks forms for singular, plural, and any other number.

plural of categorical dual