1.Lit. to mutter something to oneself so that no one else can hear. He said something to himself, but I didn't catch what it was. I said the answer to myself and no one else was supposed to hear it.
2.Fig. to think something to oneself. When I thought of him as a basketball player, I said to myself that he really isn't tall enough. I said a few choice critical remarks to myself when she presented her talk.