stock image vs pic

stock image and pic both are nouns.

Word	Noun	Adjective	Verb	Adverb
stock image	Yes	No	No	No
pic	Yes	No	No	No

As nouns, pic is a hypernym of stock image; that is, pic is a word with a broader meaning than stock image:

stock image: an existing photograph licensed for a specific use
pic: a representation of a person or scene in the form of a print or transparent slide or in digital format

Other hypernyms of stock image include exposure, photo, photograph, picture.

stock image (noun)	pic (noun)
an existing photograph licensed for a specific use	a representation of a person or scene in the form of a print or transparent slide or in digital format
	a form of entertainment that enacts a story by sound and a sequence of images giving the illusion of continuous movement