A hydrophone is an underwater microphone that detects and records sound waves and vibrations in water. However, there are various synonyms that we can use to express the same meaning. Some of these are underwater microphone, aquaphone, waterphone, and hydrophonic sensor. Another synonym for hydrophone is acoustic sensor, which is a name given to any device that can detect and record sound waves and vibrations in different materials, including water. These synonyms are useful in adding variety to our language and giving us more options to describe the same thing. Therefore, it is essential to have an extensive vocabulary to avoid repetition and make our writing more interesting and engaging.