1. Any breed of cattle with long horns, such as the English longhorn and Texas longhorn. Scottish Highland cattle also have long horns and are sometimes known as Highland longhorns.

2. (longicorn beetles) A family (Cerambycidae) of long-bodied beetles, many strikingly marked, that have very long, robust antennae. Their larvae feed on the wood of dead and dying trees. There are more than 25,000 species with a worldwide distribution.