symbol vs stock symbol

symbol and stock symbol both are nouns.

Word	Noun	Adjective	Verb	Adverb
symbol	Yes	No	No	No
stock symbol	Yes	No	No	No

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

symbol: an arbitrary sign (written or printed) that has acquired a conventional significance
stock symbol: the letters used to identify listed companies on the securities exchanges where they are traded

symbol (noun)	stock symbol (noun)
something visible that by association or convention represents something else that is invisible	the letters used to identify listed companies on the securities exchanges where they are traded
an arbitrary sign (written or printed) that has acquired a conventional significance