You searched for: “deltiology”
The hobby of collecting post cards.
deltiology (s) (noun), deltiologies (pl)
The collection and study of postcards: Deltiology has no reference to the deltic muscle. It comes from Greek deltion, "little writing tablet" and it comes from Greek deltos, "writing tablet"; so, it is presented so you will know that it has nothing to do with the other words in this delta unit.