i Register
In some senses, hey is marked as informal. Watch for register when choosing this word.
ADJ.
big, shut, silly, trying
Hey, shut your mouth if you're just going to complain about everything.
HEY + NOUN
baseball, bob, molly, pizza, tom, we're
Hey Tom, can you pick up some pizza on your way home tonight?
PREP.
about, on, up
Hey, what's up with you lately?