词根词缀：duo-, du-

【来源及含义】Latin: two, double; a word element for the number "2"

【同源单词】conduplicate, deuce, double, double-dealing, doublet, doubletalk

词根词缀：-ity

【来源及含义】Latin: suffix used to form abstract nouns expressing act, state, quality, property, or condition corresponding to an adjective

【同源单词】abnormality, absorbability, acclivity, acerbity, acridity, acrity