(Ἄδα), the daughter of Hecatomnus, king of Caria, and sister of Mausolus, Artemisia, Idrieus, and Pixodarus. She was married to her brother Idrieus, who succeeded Artemisia in B. C. 351 and died B. C. 344. On the death of her husband she succeeded to the throne of Caria, but was expelled by her brother Pixodarus in B. C. 340; and on the death of the latter in B. C. 335 his son-in-law Orontobates received the satrapy of Caria from the Persian king. When Alexander entered Caria in B. C. 334, Ada, who was in possession of the fortress of Alinda, surrendered this place to him and begged leave to adopt him as her son. After taking Halicarnassus, Alexander committed the government of Caria to her. (Arrian, Arr. Anab. 1.23; Diod. 16.42, 74; Strab. xiv. pp. 656, 657; Plut. Alex. 10.)