universus

Universus, universa, universum is unus plus versus, "turned into one", so it describes a whole taken as a single thing. Set it against omnis, which counts every item, and cunctus, which gathers them together: universa Gallia is Gaul as one entity, omnis Gallia every part of it.

The plural universi means "all at once, all together" and is the standard opposite of singuli, "one at a time" - a contrast Livy uses to explain how armies lose. The neuter singular as a noun gives universum, the universe, and the abstract universitas, "the whole body", was the medieval term for a corporation of scholars and so gave us university.