dual

• adj.
• n. 二重；二重語
• n. （二重の）人名；（仏語で）ディアール

ラテン語のduo「2」が語源。

dual

dual: [17] Dual was borrowed from Latin duālis, a derivative of duo ‘two’ (which is a distant relative of English two). In Latin it was used particularly by grammarians, to denote the category ‘two people or things’ (as opposed to the plural, referring to three or more), and this was the earliest sense of the word adopted by English. (Incidentally, despite its formal similarity, and a common meaning element – two people participate – duel [15] is not etymologically related to dual; it comes from medieval Latin duellum, which was originally an archaic form of Latin bellum ‘war’.
=> two

dual (adj.)

c. 1600, from Latin dualis, from duo "two" (see two). Related: Dually.

1. his dual role as composer and conductor

彼が作曲家と指揮者を兼任する二役

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2.He has dual role as composer and conductor.

彼は作曲家と指揮者の二重身分を兼任している.

3.The airplane had dual controls.

この飛行機には2つの操縦装置がある。

4.The reason for the discont is the use of dual -class shares.

に割引率の問題がある理由は、二重投票権株式（ dual -classshares）の使用である。

5. A safety alert system by DTMF ( Dual - tone multifrequency ) mode is introduced.

DTMF（ Dual -ToneMultifreqency）信号方式を用いて通信する安全警報システムを紹介する。