Understand is an irregular verb. Its past tense form (understood) must be memorized as it does not follow standard conjugation rules.
Verbs that follow a similar irregular pattern to understand:
| Base | Past Tense | Pattern |
|---|
Understand is irregular. Its past tense (understood) must be memorized.
Use past time markers: "Yesterday, she understood to the store."
No. Use "did not understand" (not "did not understood").
The verb understand is an irregular verb in English. Unlike regular verbs that simply add -ed, understand changes to understood in the past tense. This irregular form must be memorized as it does not follow the standard conjugation rules.
Irregular verbs like understand/understood trace back to Old English strong verbs, where vowel changes (ablaut) indicated tense shifts. Over centuries, most verbs regularized to the -ed pattern, but the most frequently used verbs retained their irregular forms because they were too common to change. This is why go/went, see/saw, and break/broke remain irregular today.
When using understood in writing, remember that it functions as a past tense verb and typically appears with time markers like yesterday, last week, or ago. For example: "Yesterday, she understood to the store." The past tense form does not change based on the subject — I understood, you understood, he/she understood, we understood, they understood.