What is the meaning of Thornback?

Any animal with a thorny back, especially marine animals, such as:

  1. The thornback guitarfish (Platyrhinoidis triseriata), a species of ray in the north-eastern Pacific Ocean.
  2. The thornback ray or thornback skate (Raja clavata), a species of ray in the Atlantic Ocean.
  3. The thornback skate (Dentiraja lemprieri), a fish endemic to Australia.

The thornback guitarfish (Platyrhinoidis triseriata), a species of ray in the north-eastern Pacific Ocean.

The thornback ray or thornback skate (Raja clavata), a species of ray in the Atlantic Ocean.

The thornback skate (Dentiraja lemprieri), a fish endemic to Australia.

A woman over a certain age (variously 26 or 30) who has never married, older than a spinster.

Source: wiktionary.org