A base ticket is one major (theme) park per day. You are allowed to re-enter the same park if you leave it on one day, but it can only be used at the one park.
If you put the ticket in the turnstile of another park the display on the Guest side of the turnstile will be "ACCESS DENIED". The top line of the display on the Greeter side will give information about the ticket, and the second line of the display will say "CROSSOVER NOT PERMITTED". The turnstile will not unlock.
This is because Disney charges $2.00 per day over five days on an adult ticket, but charges $45 to allow hopping. It does not make economic sense for Disney to allow this.