Definition

1. Noun:
   • A measuring instrument that sends out an acoustic pulse in water and measures distances based on the time for the echo to return: "Sonar" is a device used to detect and locate objects underwater by emitting sound waves and analyzing their reflections.
   • The technology or system based on this principle: "Sonar" can also refer to the general method or technique of underwater detection and navigation using sound.

Usage Examples

• Noun:
  • The submarine used its sonar to navigate safely through the dark depths.
  • Marine biologists use sonar to map the ocean floor and study whale migrations.
  • The ship's sonar detected an object several hundred meters below.

Advanced Usage

• "Active sonar": A type of sonar that emits a pulse of sound (a "ping") and listens for its echo. It is used for precise detection but can reveal the user's location.

  • The navy vessel used active sonar to search for the wreckage.

• "Passive sonar": A type of sonar that only listens for sounds made by other objects, such as ship propellers or marine life. It is used for stealthy detection.

  • The submarine relied on passive sonar to avoid detection while monitoring enemy ships.

Variants and Related Words

• ASDIC (noun): An older term, primarily British, for sonar technology used in anti-submarine warfare. It is an acronym for "Anti-Submarine Detection Investigation Committee."

  • The historical documentary explained the development of ASDIC during World War II.

• Echolocation (noun): The biological process used by animals like bats and dolphins to navigate and hunt by emitting sounds and interpreting the echoes. It is the natural counterpart to sonar.

  • Dolphins' echolocation is remarkably similar to the principle of man-made sonar.

Synonyms

• Echo sounder: A device for determining water depth by measuring the time of an echo.
• Sound navigation and ranging: The full phrase from which the acronym "sonar" is derived.

Related Phrases

• Sonar buoy (noun phrase): A floating buoy equipped with sonar, often deployed from aircraft to detect submarines.

  • The patrol plane dropped a sonar buoy to listen for submarine activity.

• Sonar image (noun phrase): A visual representation, like a map or scan, created from processed sonar data.

  • The sonar image revealed the detailed shape of the sunken ship.

Notes on Meaning

• Acronym: The word "sonar" is an acronym for Sound Navigation and Ranging. This origin is key to understanding its function.
• Primary Context: While most associated with naval and marine applications, sonar technology is also used in fishing, underwater research, and even some medical imaging techniques.

Noun

1. a measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return
   • sonar is an acronym for sound navigation ranging
   • asdic is an acronym for antisubmarine detection investigation committee