ac
ac — abbreviation
1. a common short form used in speech, messages, and product listings for an air co
a common short form used in speech, messages, and product listings for an air conditioner or for the system that cools indoor air
The hotel listing said AC was included in every room.
AC in hotel listings for room facilities
Saira turned the AC down after the baby fell asleep.
turn the AC down
Our bus had no AC, so everyone's shirts were wet by noon.
The repair crew tested the new AC before guests arrived.
Beatriz asked whether the apartment's AC worked in August.
- air conditioning
the full form; more explicit and slightly more formal than AC
- air conditioner
usually names the machine itself rather than the whole cooling system
- cooling
broader word that can describe the effect without naming the equipment
- heating
warms a space instead of cooling it
文法句型
have AC
turn the AC up/down
AC in + room/building/car
AC is on/off
用法筆記
Often refers either to the machine itself or to the cooling system for a room, car, or building. In everyday speech, people commonly say 'the AC is on' or 'the AC broke' instead of using the full term.
常見錯誤
2. a short form used in electrical talk for current that reverses direction again a
a short form used in electrical talk for current that reverses direction again and again as it moves through a circuit
The wall socket provides AC, not the direct current from batteries.
AC contrasted with battery-powered direct current
Ezra learned that AC changes direction many times each second.
core property: current changes direction repeatedly
The engineer checked whether the motor could run on AC.
This adapter turns household AC into lower-voltage power for the toy.
During class, Baraka drew a wave to explain AC on the board.
- alternating current
the full form used when the abbreviation needs to be spelled out
- AC power
common technical phrase for electrical power delivered as alternating current
- direct current
electric current that flows in one direction only
文法句型
run on AC
AC power
convert AC to DC
household AC
用法筆記
Usually appears in technical, classroom, or product-label contexts and is often contrasted with DC. Distinguish from sense 1, which is about cooling equipment in homes, vehicles, and buildings.