Heated up, it is a brand for furniture or leather items, look at Lee valley tools you can see some modern examples.A makers mark.https://www.google.com/url?sa=t&rct...evalley.com/&usg=AOvVaw2bCt-aWVuVipXGqRJSQz42 search word for it is branding irons.
How old do you think it is?