One definition given by Wiktionary for passus is "step". Another is "pace", which I understand to be two steps: the distance from where a single foot touches the ground at the start of a step and where the same foot touches down again at the start of the next step. But then I looked up the English definition of "pace" (which comes from passus) and found that it means a step or perhaps two steps. There seems to be a lot of ambiguity here.

So which is it? How many steps in mīlle passūs?

And is the distance about the same as our modern-day mile?

  • 2
    Should it be mille passus? In the plural it'd be duo milia passuum. I'm not sure if the Roman mile gets a special treatment, but regularly you shouldn't use the plural genitive with mille but with milia.
    – Joonas Ilmavirta
    Commented Jun 20 at 21:12
  • 2
    @JoonasIlmavirta I've just been googling about this and I think you're right. I learned it wrong. I just checked the placed I learned it from, Familia Romana ch. XII, and there is in fact a passage that begins Quam longus est passus?, soon followed by quīnque pedēs, mīlle passūs, and duō mīlia passuum. I'll correct it right now.
    – Ben Kovitz
    Commented Jun 21 at 1:17

2 Answers 2


The word passus means two things that are best kept separate:

  1. A step or a pair of steps.

  2. A unit of distance, five Roman feet.

Meaning 2 is inspired by meaning 1 but not tied to it. As a unit of distance it does not mean a pair of steps, but about 1.5 meters. Different people and different situations will give you vastly different lengths of step, but the meaning of passus as a unit will always mean the same. This is similar to how "foot" (either Roman or modern) means a specific length, not really the length of a foot. The L&S entry on passus quotes Pliny (Plin. 2, 23, 21, § 85) saying stadium centum viginti quinque nostros [e]fficit passus, hoc est pedes sexcentos viginti quinque, so 625 pedes is 125 passus.

The exact meaning of 1 (whether in the context of walking passus means one or two steps) is irrelevant for meaning 2. Of course two steps sounds more reasonable than one for that length, but requiring exactly two human steps is not what defines the unit.

Because passus as a unit is about 1.5 meters, mille passus is about 1.5 kilometers. This is very similar to the modern mile but not exactly the same; the figures I have seen for the Roman foot vary a bit but not enough to make the two units agree. Depending on who's walking and how, the number of steps required might range between one and ten thousand.

If you want to figure out whether passus means one or two steps, we probably need a passage from a classical author comparing passus other step-related words like gradus, gressus, incessus. If that is your main focus, perhaps another answer can handle it. This one's main point is that the meanings 1 and 2 above are distinct.

  • Thanks, Joonas! Possible correction: should officit be efficit?
    – Ben Kovitz
    Commented Jun 20 at 12:56
  • 1
    @BenKovitz You're welcome! I checked the entry again, and it has officit. Looking elsewhere, I see efficit which makes more sense. I'll edit.
    – Joonas Ilmavirta
    Commented Jun 20 at 13:03
  • 1
    On English language just found entry for a mile which talks about history of miles, gradus and Roman pace english.stackexchange.com/questions/617097/…
    – fantome
    Commented Jun 21 at 15:24
  • @fantome Do you think there might be enough material in the history of "mile", like Marcus Agrippa's standardization, to supply another answer? It would be interesting to see how and why distances have changed on the path from "passus" to "pace" and "mīlle" to "mile".
    – Ben Kovitz
    Commented Jun 21 at 17:48
  • @ben-kovitz There isn't much of anything I have to add to the answer for the above question. But a question on the evolution or history of the Roman mile, or about passus at first glance I can't see having being asked (though offhand neither do I know the answers, sorry).
    – fantome
    Commented Jun 22 at 6:37

According to Oxford "passus" = "step", "pace (5 Roman feet)"; that would be 4.86 English feet (1.48m). A big step. Therefore, a "pace" could easily be considered to be two (normal) steps.

Therein lies the ambiguity, I think.

  • 2
    Roman passus, as the movement of left foot AND movement of right foot, what in modern English is considered two steps, considered then as one pace.
    – fantome
    Commented Jun 20 at 12:04
  • @fantome: Perhaps you should read Joonas's answer.
    – tony
    Commented Jun 21 at 12:58
  • I'm sorry, but I can't see the inconsistency between my comment and in Joonas' first definition given 1. a step or pair of them. Accordingly, as even commented upon in the answer I've created the following question in Latin stack exchange specifically about the differences between gradus and passus latin.stackexchange.com/questions/23774/… latin.stackexchange.com/questions/23774/…
    – fantome
    Commented Jun 23 at 6:29

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