I saw that "donec" might mean: "as long as", but it also can mean "till". In a sense those are opposing meanings. let's consider this example:

I'm happy as long as there is daylight outside
I'm happy until there is daylight outside

Should we rely only on context (which indeed should be quite obvious), or there is a grammatical issue that makes only one of the options valid each time?

  • 4
    Another word with a similar problem is fere, which, like English 'quite,' can mean almost but not quite, or it can mean quite sure, and no argument.
    – Hugh
    Commented May 15, 2019 at 23:42
  • @Hugh, interesting! thanks for that input.
    – d_e
    Commented May 16, 2019 at 16:45
  • 1
    Funnily enough while has both these meanings in the local variety of English where I live.
    – Colin Fine
    Commented May 16, 2019 at 17:32
  • for the sake of the record, is seem another word is recingo
    – d_e
    Commented Jun 24, 2020 at 19:20
  • 1
    The technical term for these is auto-antonym.
    – cmw
    Commented Sep 16, 2021 at 1:46

3 Answers 3


Indeed, there is a grammatical explanation. If you take a close look at the L&S entry, you might notice that virtually in all the 'as long as' examples the verb is imperfect, while it's perfect in the 'until' meaning. There's a good reason for this: Latin possesses two similar temporal conjunctions, dōnec and dum, that originally were complementary and well-differentiated, but got mixed up in the course of time and of some writers' stylistic experiments:

  • dōnec is fundamentally perfective, aoristic, terminative; it denotes a point on the time scale when a change of affairs occurs: 'up until the point when'. As such, its clause normally contains a perfect verb:

    haud dēsinam dōnec perfēcerō ('I'm not going to stop until it's done'); neque crēdēbam prīmō mihimet Sōsiae, dōnec Sōsia illic egomet fēcit sibi utī crēderem ('and at first I didn't believe Sosia, that is myself, until that Sosia, that is myself, made me believe him')

  • whereas dum forms its imperfective, progressive counterpart, and denotes a stretch of time during which something did, does or will go on or hold as true: 'while, as long as'. Accordingly, its clause normally has an imperfect verb, and moreover usually in the present tense regardless of the tense of the narration:

    mihi tū, tuī, tua omnia maximae cūrae sunt et, dum vīvam, erunt ('I care greatly about you, your family and everything that is yours, and will continue to do so for as long as I live'); dum haec loquimur, ad macellum advēnimus ('while talking these things we arrived at the marketplace')

One can distinguish several specialised uses depending on tense and mood combinations between the two clauses (such as the 'expecting' subjunctive), but I won't go into this here. What's relevant to us is that at some point, dum started being used - let's say artistically - to express temporally limited actions while highlighting their progressive nature. A probable starting point for this usage can be exemplified with this:

Tītyre, dum redeō (brevis est via) pāsce capellās ('Tityrus my man, look after my goats while I'm away - I won't be long')

Literally it says 'while I'm coming back', but because the verb redīre is terminative itself, the interpretation is 'until I come back, till I return' without the need for the explicitly terminative dōnec or a perfect tense. Now, this usage itself is totally normal, but then Vergil ventures to stick a future perfect verb in there because with a future imperfect it would mean 'as long as':

bellum ingēns geret [...] tertia dum Latiō rēgnāntem vīderit aestās ('until a third summer has seen him rule in Latium')

  • Funnily enough, while looking up the passage I've stumbled upon Servius making the same observation on it in his commentary:

    'dum' autem prō 'dōnec', ut "dum conderet urbem", id est 'dōnec' ('dum here is used for dōnec, as in...')

And then everyone goes: hey, why don't us artistic types (*cough* Tacitus *cough*) flip this around by using dōnec with imperfect tenses in the function of dum? And so it came to pass; so that in late Latin both conjunctions may be used promiscuously.

If one doesn't consider themselves an artsy Latin stylist, the distinction is plain, which I'll recapitulate:

  • for 'until [a point]' use dōnec + perfect;
  • for 'while, as long as' use dum + imperfect;
  • if you see dōnec + imperfect, understand it as dum;
  • if you see dum + perfect, understand it as dōnec;
  • dōnec + impf. subj. for reaching an (undesirable) tipping point may be a special case, contrasting with the progressively anticipating dum + impf. subj.

Donec denotes the relationship between two actions, at the same time e.g.

"donec, infecta pace, armis desilirent" giving ""while", with peace having been broken off, they came to strive with arms";

"...et non cognoscebat eam, donec peperit filium, et vocavit nomen eius Iusum." giving "...and he did not know (have carnal-knowledge of) her "until" she had given birth to a son, and the name of him she called Jesus." Hence, or otherwise: "He did not have sexual relations with her for "as-long-as" she was pregnant."

Apologies for sparsity, earlier; didn´t want to claim other´´s work as own. The Wiki entry has required some embellishment, however.

With problems like this, type in the word, nothing else, a Wiki-option will appear. If the net cannot identify the word as Latin, it´´s too similar to its English descendant, then add "Latin," followed by the word.

  • 2
    Can you elaborate more on this? This looks like a nice start of an answer, but it doesn't really get to explaining how the two seemingly opposite meanings arise.
    – Joonas Ilmavirta
    Commented May 16, 2019 at 16:46

Really, this is just a quirk of the language. All languages have quirks, including our own. Consider 'up to':

It's up to you...It came up to scratch...I got up to the top...I filled it up to the top.

And here the opposite can mean the same: It's down to you....

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