IELTS hum Definition To make or produce a low, steady continuous sound. Example "The refrigerator began to hum after it was plugged in." Sign in to save IELTS PDF — $25 ← hull humane → Study tips featuring "hum" Boost Your IELTS Writing With Precise Vocabulary Related words TOEFL brighten IELTS startle GRE abide SAT abnormal TOEFL aboard TOEFL abolition IELTS upward TOEFL abort IELTS abortion SAT abrupt SAT absence TOEFL absent