Fears that the dye would harm the reef proved unfounded, though the monitoring continued for another decade.
担心染料会危害珊瑚礁的说法被证明毫无根据，不过监测又持续了十年。
Which choice best defines “unfounded”?
C — Not based on fact or evidence.. “unfounded” means Not based on fact or evidence..
Which word means “Not based on fact or evidence.”?
C — unfounded. “unfounded” means Not based on fact or evidence..
unfounded — Not based on fact or evidence.. In Chinese: 毫无根据的;凭空的.
unfounded is pronounced //ʌnˈfaʊndɪd//.
Fears that the dye would harm the reef proved unfounded, though the monitoring continued for another decade. (担心染料会危害珊瑚礁的说法被证明毫无根据，不过监测又持续了十年。)
baseless, groundless, unsubstantiated — all close in meaning to unfounded (Not based on fact or evidence.).
justified, substantiated — each the opposite of unfounded (Not based on fact or evidence.).
Yes. unfounded is on the SAT Prep Difficult list — the higher-register words that decide the hard questions. The Digital SAT does not test vocabulary in isolation; words like this one are tested through Words in Context questions, where you choose the word that completes a passage most logically and precisely.
un(无) + founded(有根据的) → 没有依据 → 毫无根据的。