# ohm

/ˈoʊm/ (US) · /ˈəʊəm/ (UK) · CEFR C2 · Noun

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

## Definition

the standard unit used to measure how much a material resists the flow of electricity. A higher number means it is harder for the current to pass through.

For teachers: the SI unit of electrical resistance, equal to the resistance of a circuit in which a potential difference of one volt produces a current of one ampere. Named after the German physicist Georg Simon Ohm.

## Examples

- The speaker has an impedance of eight ohms.
- To protect the LED from burning out, the engineer added a ten-ohm resistor to the circuit.
- The precision of the measurement was critical, as even a fraction of an ohm could significantly alter the performance of the high-frequency transmitter.

## Usage notes

- Often represented by the Greek letter omega (Ω).

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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.