ice cube vs cube

ice cube and cube both are nouns.

Word	Noun	Adjective	Verb	Adverb
ice cube	Yes	No	No	No
cube	Yes	No	Yes	No

As nouns, cube is a hypernym of ice cube; that is, cube is a word with a broader meaning than ice cube:

Other hypernyms of ice cube include square block.

ice cube (noun)	cube (noun)
a small cube of artificial ice; used for cooling drinks	a block in the (approximate) shape of a cube
	any of several tropical American woody plants of the genus Lonchocarpus whose roots are used locally as a fish poison and commercially as a source of rotenone
	the product of three equal terms
	a hexahedron with six equal squares as faces
	a three-dimensional shape with six square or rectangular sides

ice cube (verb)	cube (verb)
	raise to the third power
	cut into cubes