nit: the suffix -um in latin typically indicates a neuter grammatical gender. -us is usually masculine, and only in its accusative form it becomes -um. there ar

nit: the suffix -um in latin typically indicates a neuter grammatical gender. -us is usually masculine, and only in its accusative form it becomes -um. there are exceptions though, e.g. feminine 'manus' (hand). https://en.m.wikipedia.org/wiki/Latin_declension https://en.m.wikipedia.org/wiki/Latin_declension