asdic vs echo sounder

asdic and echo sounder both are nouns.

Word	Noun	Adjective	Verb	Adverb
asdic	Yes	No	No	No
echo sounder	Yes	No	No	No

As nouns, asdic and echo sounder are synonyms defined as:

asdic and echo sounder: 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

Other synonyms of asdic include sonar.

asdic (noun)	echo sounder (noun)
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	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