if two people go back a particular period of time, they have known each other for that period of time
Example: After one drink they went back to her bedsit.
to have existed since or for a particular time
Example: Don’t forget, the clocks go back this Sunday.
to return to a person, place, subject, or activity
Example: Go back a century or more, and the church will be found at the centre of English village life.
when schools or students go back, classes begin again after a long holiday
Example: He then got married and yet within a month dumped the new one and went back to the original.
when the clocks go back, everyone changes the time on their clocks so that they show a time that is one hour earlier than before
Example: It started to rain, so we decided to go back.