Enrol
Another word for enrolls could be sign- up or matriculation, or enlist.
Constellation or zodiac sign
character, sign
Call sign?
yes
up and down
I have listed this as part of another answer here: What_is_sign_for_king_in_asl
sign, prediction, warning, prenotion
Placard , notice , poster or sign .
Mercedes logo, maybe
sympton
Another word for shut up is Insturd