leo

Leo, leonis is third declension masculine, borrowed early from Greek leon. Latin never built a native feminine from the stem either, taking leaena from Greek as well. The comparison fortis ut leo is stock, and the ablative of comparison, fortior leone, saves you the quam.

The practical trap in a corpus like this one is that Leo is a man's name at least as often as it is an animal. Thirteen popes and several saints were called Leo, so a capitalised Leo in an ecclesiastical text is almost certainly a person, and Leo Magnus is Pope Leo the Great rather than a large cat. Theologically the beast cuts both ways: the devil prowls as a roaring lion, and Christ is the Lion of Judah. English keeps leonine and, through French dent de lion, the dandelion.