test tube vs tubing

test tube and tubing both are nouns.

Word	Noun	Adjective	Verb	Adverb
test tube	Yes	No	No	No
tubing	Yes	No	No	No

As nouns, tubing is a hypernym of test tube; that is, tubing is a word with a broader meaning than test tube:

test tube: glass tube closed at one end
tubing: conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases

Other hypernyms of test tube include tube.

test tube (noun)	tubing (noun)
glass tube closed at one end	conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases