button vs panic button

button and panic button both are nouns.

Word	Noun	Adjective	Verb	Adverb
button	Yes	No	Yes	No
panic button	Yes	No	No	No

As nouns, panic button is a hyponym of button; that is, panic button is a word with a more specific, narrower meaning than button:

button: an electrical switch operated by pressing
panic button: a button to push in order to summon help in case of an emergency

Other hyponyms of button include bell push, bell, buzzer, doorbell, horn button, mouse button, reset button.

button (noun)	panic button (noun)
a round fastener sewn to shirts and coats etc to fit through buttonholes	a button to push in order to summon help in case of an emergency
an electrical switch operated by pressing
a device that when pressed will release part of a mechanism
any artifact that resembles a button
a specific area or icon in graphical user interface systems that is clicked or pressed in order to select a command or perform an action
a female sexual organ homologous to the penis
a round flat badge displaying information and suitable for pinning onto a garment
any of various plant parts that resemble buttons

button (verb)	panic button (verb)
fasten with buttons
provide with buttons