Dominus illuminatio mea

Question

I am trying to understand this expression. According to Wikipedia, it is translated as "The Lord is my light".

Before reading this article, I thought this meant "Lord illuminate me", perhaps in imperative mode. In effect, there is such verb - illuminare, and I was trying to find the specific conjugation which would tell me the mode, time, person, etc. But that seem not to exist.

Would my original interpretation be written "Dominus illumina mea"?

More generally, how to precisely differentiate among such words that are both a noun and a verb? Is it plainly obvious that a declinsion "tio" is not a verb? Is there another clue?

Answer 1

The verb est is omitted but implied. The motto is taken from the start of Psalm 27 (or 26):

Dominus illuminatio mea et salus mea; quem timebo?
Dominus protector vitae meae; a quo trepidabo?

The Lord is my source of light and my salvation; whom shall I fear?
The Lord is the protector of my life; by whom shall I be made to tremble?

Putting in the omitted ests:

Dominus illuminatio est mea et salus mea; quem timebo?
Dominus protector est vitae meae; a quo trepidabo?

Omitting a copula verb is quite common in Latin. Here's a sample from Varro, Lingua Latina, V.4, proposing an etymology of the word terra. I've indicated the missing copulae in the English translation:

Terra dicta ab eo, ut Aelius scribit, quod teritur. Itaque tera in augurum libris scripta cum R uno. Ab eo colonis locus communis qui prope oppidum relinquitur teritorium, quod maxime teritur.

Terra [Earth] is said because, as Aelius writes, it is trodden on [i.e. the root of the verb tero sounds like terra]. And so it is written tera, with one R, in the books of the augurs. For the same reason, the communal place near a town that is left to the farmers is called the teritorium, because it gets trodden on the most.

^{(Varro's etymology is mistaken according to modern scholarship, and he seems to have misspelled territorium.)}

Omitting the copula is especially common in proverbs and mottos:

In vino veritas. (There is truth in wine.)
Scientia potentia. (Knowledge is power.)
Dulce bellum inexpertis. (War seems sweet to those who haven't experienced it.)
Caesar non supra grammaticos. (Caesar is not above the grammarians.)

Answer 2

Imperatives have a distinct form, and they can never end in -tio. You can have verbs that end in -tio, though, like sentio, but the -o ending indicates that it's first person singular. Far more often the -tio ending is used for nouns that are derived from verbs. The past passive participle ends in -tus (or -sus in some cases), and from the stem the -tio ending is added. This is similar to the Spanish -ción.

As far as how to translate the phrase, if you wanted to say, "Lord, illuminate me," you would have to change everything.

For one, since you're addressing the Lord, the Latin would have to be in the vocative, domine instead of dominus.

Second, you would have to say "me" instead of "my", so me and not mea.

Finally, as you noticed, illumina is the imperative of illuminare, so you're correct on that. Putting it all together you'd get:

Domine, me illumina. Do note though that this doesn't mean "make me enlightened," at least not in Classical Latin, but rather, "Lord, make me illustrious," or, "Lord, shine a light on me (so that others can see how good I am)."