control grid vs tube

control grid and tube both are nouns.

Word	Noun	Adjective	Verb	Adverb
control grid	Yes	No	No	No
tube	Yes	No	Yes	No

control grid (noun)	tube (noun)
an electrode placed between the cathode and anode of a vacuum tube to control the flow of electrons through the tube	conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases
	an electric railway operating below the surface of the ground (usually in a city)
	electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope
	(anatomy) any hollow cylindrical body structure
	a hollow cylindrical shape

control grid (verb)	tube (verb)
	place or enclose in a tube
	convey in a tube
	ride or float on an inflated tube
	provide with a tube or insert a tube into