The young of cats are called kittens or cubs, depending partly on how large the cat is, and apparently partly on informal custom. Wikipedia, kitten says:
The word "kitten" derives from the Middle English word kitoun, which in turn came from the Old French chitoun or cheton. Juvenile big cats are called "cubs" rather than kittens; either term may be used for the young of smaller wild felids, such as ocelots, caracals and lynx, but "kitten" is usually more common for these species.
So far, clear. But take a look at the name for the young of cougars.
The young of mountain lions are often called kittens. This seems an odd choice for the young of such a large cat. Wikipedia says:
Cougars are the largest of the small cats. They are placed in the subfamily Felinae, although their bulk characteristics are similar to those of the big cats in the subfamily Pantherinae.
Cougar: The American Lion, a publication of the Mountain Lion Foundation says:
Newborn mountain lions enter the world as buff brown balls of fur weighing slightly more than a pound. Biologists call them kittens or cubs either is correct.
This article then proceeds to call them kittens throughout.
Sciencing calls them cubs.
Is there a scientific basis for choosing kittens over cubs, or vice versa, for the young of cats? The extremes are clear: a baby tiger is a cub; a baby domestic cat is a kitten. But in the middle -- is there a scientific rule or just personal preference?