What is a meow?

From what I understand, silent meow is something cats do to show their gratitude and affection. A relaxed or interested-in-you cat, with ears up, narrows his or her eyes and opens his or her mouth widely, as if to meow, but makes no sound. I have a female cat who does this, and male who doesn't (but is affectionate in other ways she isn't), and there's no mistaking it for anything but a sign of affection. Consider yourself lucky -- and complimented -- if you see it.