Smile is the thing you do with your face when you are happy -– or want others to think you are. Your expression softens and your mouth turns up at the corners.
Smile, noun or verb, with its universal message and association with enjoyment and pleasure, is a very useful word. It can express joy or even say hello. Of course if you “smile through your sorrows,” you are either tying to make yourself feel better or fool other people into thinking you are happy. But in general, a smile is a good sign. And as the song goes “You’re never fully dressed without a smile.”