- dyad (n.)
[dyad 词源字典] - 1670s, from Latin dyad-, stem of dyas, from Greek dyas "the number two, a group of two," from duo "two" (see two). Specific sense in chemistry ("a bivalent element") is by 1865; also used in biology, poetics, mathematics. Related: Dyadic.[dyad etymology, dyad origin, 英语词源]
