氘 dāo — deuterium (D, hydrogen-2) 氘 dāo Level 2 · Frequent #3599 dāo dao1 Basic definition noun deuterium (D, hydrogen-2) e.g 氘气氘核 Detailed explanation noun deuterium Related words 氘气 dāo qì deuterium gas 氘核 dāo hé a deuterium nucleus