The suffix -phone (from Greek φωνή ‘sound [of the voice], voice, sound, tone’) is a very productive one, appearing in several senses. These include the following:
‘sound’ (as in homophone)
‘producing sound’ (as in xylophone)
‘transmitting sound’ (as in telephone)
‘monitoring sound’ (as in sphygmophone)
‘speaking a language’ (as in Francophone)
This multiciplicity of related meanings has occasionally resulted in what are essentially homographic homophones, i.e., words that are spelled and pronounced the same but have different histories and meanings. For example, a hydrophone is both (a) a medical device used in auscultation involving the amplification of a person’s organs through a column of water and (b) according to the OED, “An instrument devised to give warning by electricity to a port or fleet of the approach of a hostile vessel.”
The following link takes you to a short list of such words, each of which is accompanied by three examples or definitions, two of which are correct and the other of which is not. Can you spot the phonies?