Select the most appropriate one-word substitution for the given group of words.

An instrument which is used to measure atmospheric pressure 

Barometer

The most appropriate one-word substitution for "an instrument which is used to measure atmospheric pressure" is barometer.

• Ammeter is an instrument used to measure electric current.
• Fathometer is an instrument used to measure the depth of water.
• Anemometer is an instrument used to measure wind speed.
• Barometer is an instrument used to measure atmospheric pressure.