Geologists detected a slight irregularity in the rock layers, suggesting a past seismic event that had gone unnoticed.
地质学家在岩层中检测到轻微的不规则性，表明过去曾发生过未被注意到的地震事件。
Which choice best defines “irregularity”?
B — Something that is not usual or normal. “irregularity” means something that is not usual or normal.
Which word means “something that is not usual or normal”?
A — irregularity. “irregularity” means something that is not usual or normal.
irregularity — something that is not usual or normal. In Chinese: 不规则，不正常.
irregularity is pronounced /ɪˌrɛɡjəˈlærəti/.
Geologists detected a slight irregularity in the rock layers, suggesting a past seismic event that had gone unnoticed. (地质学家在岩层中检测到轻微的不规则性，表明过去曾发生过未被注意到的地震事件。)
anomaly, aberration, deviation — all close in meaning to irregularity (something that is not usual or normal).
regularity, consistency — each the opposite of irregularity (something that is not usual or normal).
Yes. irregularity 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.