This is the 3442nd most frequent Polish word.
zapomnieli
"Zapomnieli" means "they forgot" in English.
The word 'zapomnieli' is used here as the third person plural past tense of 'zapomnieć,' indicating that a group of people forgot something.
Zapomnieli przynieść klucze na spotkanie.
They forgot to bring the keys to the meeting.
In this sentence, 'zapomnieli' again serves as the verb indicating forgetfulness, matching the grammatical number and tense with the subject (children).
Dzieci zapomnieli o zadaniu domowym.
The children forgot about their homework.
Here, the verb 'zapomnieliśmy' is the first person plural past tense of 'zapomnieć,' meaning 'we forgot,' which shifts the subject to the speaker including others.