# hum

/ˈhəm/ (US) · /hˈʌm/ (UK)

Source: https://englishreference.com/word/hum
Updated: 2026-08-15

## Senses

### 1. to sing with closed lips

verb · CEFR B1

to make a musical sound with your voice while keeping your mouth closed.

For teachers: to produce a melodic tone from the vocal cords without articulation, typically with the lips closed.

- She hummed a happy tune while she was cleaning the kitchen.
- The composer sat at the piano, humming a tentative melody before committing the notes to the manuscript paper.

### 2. to make a low drone

verb · CEFR B1

to make a continuous low sound like a machine or a bee.

For teachers: to produce a continuous low-frequency sound, characteristic of insects in flight or electrical machinery.

- The refrigerator hums quite loudly during the night.
- The server room hummed with the constant vibration of cooling fans and high-speed processors.

### 3. to be very busy

verb · CEFR B2 · Informal

to be full of activity and energy.

For teachers: to be in a state of intense, productive activity or excitement.

- By ten o'clock, the office was really humming with activity.
- The factory floor was humming as the team worked overtime to meet the end-of-quarter production targets.

### 4. to smell bad

verb · CEFR C1 · British English · Slang · Informal

to have a very strong and unpleasant smell.

For teachers: to emit a powerful and offensive odour. Intransitive use.

- Those old gym shoes are starting to hum.
- After a week without a working fridge, the entire kitchen began to hum with the scent of spoiled milk.

Teaching tip: This sense is specific to British English and is quite informal; use 'stink' or 'smell' in more neutral contexts.

### 5. a low sound

noun · CEFR B1

a low, steady, continuous sound.

For teachers: a continuous low-pitched sound, such as that made by a motor or a distant crowd.

- There was a constant hum of traffic from the nearby highway.
- The quiet hum of the air conditioning was the only sound in the deserted library.

## Examples

- She likes to hum a happy tune while she works.
- The old refrigerator started to hum loudly in the middle of the night.
- The entire server room began to hum with a low-frequency vibration that seemed to resonate through the floorboards of the office above.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.