# fool with

CEFR B2 · Phrasal verb

Source: https://englishreference.com/word/fool-with
Updated: 2026-04-24

## Definition

to play with something in a careless way or to waste time on something that is not important.

For teachers: to handle something idly or meddle with a mechanism; can also mean to engage in casual or aimless activity with a person or object.

## Examples

- Don't fool with the thermostat or the house will get too hot.
- He spent the whole afternoon fooling with his old car engine but couldn't get it to start.
- The technician warned the staff not to fool with the calibration settings, as even a minor adjustment could compromise the entire experiment.

## Pitfalls

- Not "He is fooling with of the radio." but "He is fooling with the radio." — the preposition 'with' is the only particle needed before the object; do not add 'of'.

## Usage notes

- often used as a warning or to describe unproductive behavior.
- Teaching tip: contrast with 'mess with' which is more common in modern speech; 'fool with' can imply a lack of seriousness or expertise.

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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.