tag vs tag along

tag is a noun but tag along is not a noun.

Word	Noun	Adjective	Verb	Adverb
tag	Yes	No	Yes	No
tag along	No	No	Yes	No

tag (noun)	tag along (noun)
(sports) the act of touching a player in a game (which changes their status in the game)
a game in which one child chases the others; the one who is caught becomes the next chaser
a small piece of cloth
a label written or printed on paper, cardboard, or plastic that is attached to something to indicate its owner, nature, price, etc.
a label associated with something for the purpose of identification

tag (verb)	tag along (verb)
provide with a name or nickname	go along with, often uninvited
attach a tag or label to
touch a player while he is holding the ball
supply (blank verse or prose) with rhymes
go after with the intent to catch