The rapid melting of Arctic ice in the past decade has reached an unprecedented rate, alarming climate scientists worldwide.
过去十年北极冰层的快速融化已达到史无前例的速度，令全球气候科学家感到震惊。
The essay opens by acknowledging that social media has connected distant friends and family in unprecedented ways, but the bulk of the essay focuses on documenting its effects on attention span and in-person social skills.
From a Text Structure and Purpose question · Craft and Structure
Which choice best defines “unprecedented”?
D — Never happened before. “unprecedented” means never happened before.
Which word means “never happened before”?
D — unprecedented. “unprecedented” means never happened before.
unprecedented — never happened before. In Chinese: 史无前例的.
unprecedented is pronounced /ʌnˈpresɪdentɪd/.
The rapid melting of Arctic ice in the past decade has reached an unprecedented rate, alarming climate scientists worldwide. (过去十年北极冰层的快速融化已达到史无前例的速度，令全球气候科学家感到震惊。)
novel, unheard-of, unexampled — all close in meaning to unprecedented (never happened before).
ordinary, commonplace — each the opposite of unprecedented (never happened before).
Yes. unprecedented is on the SAT Prep Easy list — mid-frequency academic words that do get tested. 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(not)+precedent(precedent).