old, advanced in age(from the practice of judging a horse's age by the length of it's teeth)
The plumbing is a bit long in the tooth. It needs to be replaced.
(adj.) Old, outdated. no longer to perform its primary function at optimum level.
The playstation one is a bit long in the tooth these days.
A women who has passed her prime
"Hey John, is your new secratary hot?"
"No, she is a little long in the tooth."