Use trusty to describe something you can count on, especially if you've relied on it for a long time. You don't need a fancy bike—your trusty roller skates will get you to school on time!
This informal adjective is perfect for talking about people and objects that are tried-and-true, even if they're a little worn out. If your friend shows off her brand new laptop, you could say, "I'm happy with my trusty old typewriter!" Before the 14th century, trusty meant "trusting." As a noun, it can also be used to mean "trustworthy person," particularly a prisoner who has shown good conduct.