thornback

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

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

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

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

[A] society of honest gentlemen [is holding a lottery] for the benefit of all single ladies, widows, maids, or thornbacks […]

Spinsters. — In a society where marriages were formed very early, girls often wedding at sixteen or under, […] At the age of thirty a spinster was called a "thornback ,” but bachelors and thornbacks were not the only people who […]