Huffy means in a bad mood because you feel someone has been rude to you, or has not given you the respect you wanted. It is a small, proud kind of anger — closer to sulking than to a big fight. A huffy person may go quiet, stick their chin out, or leave the room. Family talk and light writing use it; it is not a hard or formal word. It is a little old-fashioned in some places, but people still understand it at once. It comes from huff (a puff of breath, or a little sulk) plus -y, meaning “full of that feeling.”