Things that are true are accurate, honest, and correct. There are many specific meanings, but when something is true, you can believe it.
This word has many meanings, but they're all pretty much the opposite of false. True statements can be proven or verified — they aren't lies. To sing true is to sing on-key, and a true throw is on-target. The true king is the real king, not a fake. A true friend can be trusted. A true believer really believes in something, like a religion. And when you're true to yourself, you're being honest about what you want and feel.