sing vs emit

sing and emit both are verbs.

Word	Noun	Adjective	Verb	Adverb
sing	No	No	Yes	No
emit	No	No	Yes	No

As verbs, emit is a hypernym of sing; that is, emit is a word with a broader meaning than sing:

Other hypernyms of sing include let loose, let out, utter.

sing (verb)	emit (verb)
make a whining, ringing, or whistling sound	expel (gases or odors)
divulge confidential information or secrets	express audibly; utter sounds (not necessarily words)
to make melodious sounds	give off, send forth, or discharge; as of light, heat, or radiation, vapor, etc.
produce tones with the voice
deliver by singing