to go somewhere secretly, trying to avoid being seen

to do something or take somebody/something somewhere secretly, often without permission

If the gate is open, you can sneak a peek at the gardens.

At last we were able to sneak a moment alone together.

to secretly take something that is small or unimportant

I sneaked a cake when they were out of the room.

to tell an adult that another child has done something wrong, especially in order to cause trouble

Did you sneak on me to the teacher?

a person, especially a child, who tells somebody about something wrong that another person has done

LEARNit Dictionary