wasting away vs symptom

wasting away and symptom both are nouns.

Word	Noun	Adjective	Verb	Adverb
wasting away	Yes	No	No	No
symptom	Yes	No	No	No

As nouns, symptom is a hypernym of wasting away; that is, symptom is a word with a broader meaning than wasting away:

wasting away: a decrease in size of an organ caused by disease or disuse
symptom: (medicine) any sensation or change in bodily function that is experienced by a patient and is associated with a particular disease

wasting away (noun)	symptom (noun)
a decrease in size of an organ caused by disease or disuse	anything that accompanies X and is regarded as an indication of X's existence
	(medicine) any sensation or change in bodily function that is experienced by a patient and is associated with a particular disease