The surveyor ensured that each wall was perfectly perpendicular to the floor, preventing structural instability.
测量员确保每面墙都与地面完全垂直，以防止结构不稳定。
Which choice best defines “perpendicular”?
C — At an angle of 90 degrees to a given line, plane, or surface. “perpendicular” means at an angle of 90 degrees to a given line, plane, or surface.
Which word means “at an angle of 90 degrees to a given line, plane, or surface”?
B — perpendicular. “perpendicular” means at an angle of 90 degrees to a given line, plane, or surface.
perpendicular — at an angle of 90 degrees to a given line, plane, or surface. In Chinese: 垂直的，直立的.
perpendicular is pronounced /ˌpɜːrpənˈdɪkjələr/.
The surveyor ensured that each wall was perfectly perpendicular to the floor, preventing structural instability. (测量员确保每面墙都与地面完全垂直，以防止结构不稳定。)
vertical, upright, orthogonal — all close in meaning to perpendicular (at an angle of 90 degrees to a given line, plane, or surface).
parallel, horizontal — each the opposite of perpendicular (at an angle of 90 degrees to a given line, plane, or surface).
Yes. perpendicular is on the SAT Prep Basic list — the everyday academic words the SAT assumes you already have. 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.