punctum

Punctum, puncti, n., second declension. It is not really a noun at all to begin with but the neuter perfect participle of pungo, "to prick", frozen into one: a punctum is a pricked mark. From the dot come the geometric point, the mark of punctuation, and the vote, since Roman ballots were counted by pricking a tablet, which is why omne tulit punctum means to carry every vote and so to win outright.

The temporal sense is the one that survives best: punctum temporis, "a point of time", an instant. Medieval scribes use it for the divisions of the day and for a paragraph in an argument. English takes point, punctual, puncture and pungent from the same prick.