If you pat something or someone, you tap them lightly, usually with your hand held flat.

A pat of butter or something else that is soft is a small lump of it.

If you say that an answer or explanation is pat, you disapprove of it because it is too simple and sounds as if it has been prepared in advance.

If you give someone a pat on the back or if you pat them on the back, you show them that you think they have done well and deserve to be praised.

If you have an answer or explanation down pat or off pat, you have prepared and learned it so you are ready to say it at any time.

If you stand pat, you refuse to change your mind about something.