hy·dro·phone 
(hīdrə-fōn′)
(hīdrə-fōn′)n.
An electrical instrument for detecting or monitoring sound under water.
- common noun
- commonplace
- commonplace book
- common pleas
- common room
- common salt
- common school
- common seal
- common sense
- common-sense
- commonsensical
- common-site picketing
- common-situs picketing
- common stock
- common time
- common touch
- commonweal
- commonwealth
- Commonwealth of Independent States
- Commonwealth of Nations
- common year
- commotion
- commove
- communal
- communalism