What does ampere mean?
The ampere is the SI base unit of electric current, symbol A, measuring the rate at which electric charge flows through a conductor. One ampere corresponds to one coulomb of charge passing a given point each second. Named after the French physicist André-Marie Ampère, a founder of electrodynamics, it sits alongside the volt and the ohm as one of the fundamental quantities of electrical science: voltage provides the pressure that drives current, resistance opposes it, and the ampere quantifies the flow itself. In everyday use the word is nearly always abbreviated to 'amp' or 'amps', appearing on fuses, chargers, circuit breakers, and power supplies, while the full term 'ampere' is reserved for formal scientific writing, engineering specifications, and legal standards. Because every electrical device is rated for the current it draws or delivers, the ampere is among the most practically encountered of all scientific units, essential for understanding everything from household wiring safety to battery capacity, where ampere-hours express how much charge a battery can store.
nounThe ampere is the SI base unit of electric current, equal to one coulomb of charge passing a point per second. Informally shortened to 'amp', it measures the rate of flow of electric charge in a circuit.
- The SI base unit of electric current, defined as one coulomb of charge per second.
- Informally, the amount of electric current drawn or delivered by a device or supply (usually expressed as 'amps').
"The fuse is rated at fifteen amperes, so anything drawing more current will blow it."
"Household circuits in North America are typically rated for fifteen or twenty amperes."
"The charger delivers up to three amps of current to fast-charge the battery."
Standard plural; in informal usage 'amps' is far more common.
"The service panel supplies two hundred amperes to the house."
Every electrical device you own draws its lifeblood in amperes — a unit named after a French physicist who taught himself mathematics using his father's library by age twelve.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of ampere
The word 'ampere' is an eponym adopted in the late nineteenth century, honoring André-Marie Ampère (1775–1836), the French physicist and mathematician whose pioneering work on electromagnetism laid the foundations of electrodynamics. The term entered English from French, where Ampère's name had already been attached to the unit during the early standardization of electrical measurement. It was formally established internationally when the ampere was incorporated into the SI system in the mid-twentieth century, and it remains one of the seven SI base units today.
Related word forms
How ampere is actually used
In everyday and technical speech the word is almost always shortened to 'amp' (plural 'amps'); the full form 'ampere' appears mainly in formal, scientific, legal, and standards contexts. As an SI base unit it is written lowercase ('ampere') but its symbol is capitalized ('A').
Easily confused with ampere
'Amp' is simply the informal short form of the ampere, not a different quantity.
A volt measures electrical potential difference (pressure), whereas an ampere measures the resulting current (flow).
An ohm measures resistance to current flow, while the ampere measures the current itself.