water vs O

water and O both are nouns.

Word	Noun	Adjective	Verb	Adverb
water	Yes	No	Yes	No
O	Yes	No	No	No

water (noun)	O (noun)
a facility that provides a source of water	the blood group whose red cells carry neither the A nor B antigens
a liquid necessary for the life of most animals and plants	the 15th letter of the Roman alphabet
the part of the earth's surface covered with water (such as a river or lake or ocean)	a nonmetallic bivalent element that is normally a colorless odorless tasteless nonflammable diatomic gas; constitutes 21 percent of the atmosphere by volume; the most abundant element in the earth's crust
binary compound that occurs at room temperature as a clear colorless odorless tasteless liquid; freezes into ice below 0 degrees centigrade and boils above 100 degrees centigrade; widely used as a solvent
liquid excretory product
once thought to be one of four elements composing the universe (Empedocles), associated with the humour phlegm

water (verb)	O (verb)
secrete or form water, as tears or saliva
supply with water, as with channels or ditches or streams
fill with tears
provide with water