Here's where the third declension gets complicated. In the last two chapters, it's been simple: drop the -is ending from the genitive to get the stem, add our third declension endings, and remember that the neuter accusative matches the nominative and takes -a in the plural. Simple enough. But now we've got a whole new class of third declension nouns that work a bit differently: the I-stems.

First of all, I'm not really sure why they're called I-stems, because the stem doesn't really end in -i-! My textbook says, “These nouns normally show the -i- of the stem only in the genitive plural…” To my mind, if it only shows up in one form out of ten, it's not part of the stem; it's part of the ending, or an extra part in between, like the tense-signs we've learned for verbs. But “I-stems” are what all the books call them, so we will too.

So how do we tell I-stems from other third declension nouns? There are four different types of I-stems:

1. Masculine and feminine nouns ending in -is or -ēs in the nominative singular, with the same number of syllables in the nominative and genitive. (Note that that's a long -ē- in -ēs, not a short one. So mīles, mīlitis, which we learned two lessons ago, does not match this rule.) For example:

• cīvis, cīvis, m. or f., citizen
• caedēs, caedis, f., murder

2. Masculine and feminine nouns ending in -rs or -ns in the nominative singular:

• mors, mortis, f., death
• pōns, pontis, m., bridge

3. Masculine and feminine nouns with a single syllable in the nominative, and a genitive stem that ends in two consonants:

• nox, noctis, f., night
• urbs, urbis, f., city

4. Neuter nouns ending in -al or -e in the nominative singular.

• animal, animālis, n., animal
• mare, maris, n., sea

All I-stems fall into one of those four categories, three for masculine and feminine nouns and one for neuter nouns. If a third declension noun (one that ends in -is in the genitive singular) doesn't match one of these rules, it's not an I-stem, and is declined according to the rules we learned in lessons 14 and 15.

Now that we know how to recognize them, how do we decline them? The answer is: almost exactly the same as non-I-stems. For masculine and feminine nouns, the only difference is in the genitive plural; the -i- of the “stem” shows up before the -um ending. So if we compare miles (not an I-stem) to hostis (an I-stem), we see that everything else is the same:

Things differ more in the neuter forms. In the neuter, the -i- shows up in the genitive plural, but also before the -a ending of the nominative and accusative plural, and it becomes long and replaces the -e ending of the ablative singular. Let's compare corpus (not an I-stem) and animal (an I-stem) to show the differences:

The neuter I-stems have more quirks than the masculine and feminine ones, but it's still a minority of the forms. Luckily, there are very few neuter I-stem nouns. The two we learn in this lesson may be the only two we see for a long time.

• animal, animālis, n., animal
• caedēs, caedis, f., murder
• cīvis, cīvis, m. or f., citizen
• fīnis, fīnis, m., end, boundary; (plural) territory
• gēns, gentis, f., family, clan, tribe
• hostis, hostis, m., enemy
• ignis, ignis, m., fire
• īnfans, īnfantis, m., baby
• mare, maris, n., sea
• mōns, montis, m., mountain, hill
• mors, mortis, f., death
• nāvis, nāvis, f., ship
• nox, noctis, f., night
• pānis, pānis, m., bread
• pōns, pontis, m., bridge
• urbs, urbis, f., city

When Romans wanted to sound like a President giving a speech, they said, “cīvēs mei,” which translated literally means, “my citizens,” but to them meant, “my fellow citizens.”

Fīnēs (the plural of fīnis) means “territory” in the geographical sense because multiple boundaries define a particular area. Where we would say “in the territory of the Romans,” they would say, “in the boundaries of the Romans”: in finibus Romanorum.

Earlier we learned inimicus, which means a personal enemy. Now we've learned hostis, which means an enemy of the state or a military foe. Note that Latin speakers never used “enemy” in the singular to refer to a hostile army, the way we often do in English:

• The enemy is at the gate. - Hostes sunt in porta. (Literally: “The enemies are at the gate.)

“Sea” is one of the few words that still has a sort of gender in English, where it is often referred to as “she,” yet it was a neuter noun (mare) in Latin. Go figure. “Ship” (navis), on the other hand, is feminine in both languages.

• mare latum
• mons albus
• navis nova

1. Animalia in navem in flumine ambulaverunt.
2. Cives mei, laudate Deum.
3. Gens nostra in finibus Germanorum habitabunt.
4. Castra hostium telis et igne oppugnavimus.
5. Nauta trans mare magna cum audacia navigavit.
6. Servi panem viris et feminis dant et frumentum animalibus.
7. Pueri a parvo oppido ad magnam urbem ante bellum ambulaverant.
8. Oppugnavi inimicum meum gladio; vulnera erant multa et magna.
9. Ambulate, pueri, sub montem, et exspectate ibi signum belli.
10. Equus albus magnus in ponte stabat.

1. Why did the enemy attack our little town with fire?
2. The Roman people are our allies, aren't they?
3. Many citizens praised the death of the bad consul.
4. Our journey across the sea was long.
5. After Caesar's death, there were many new poems about (his) reign.
6. Shall we seize the territory of the Greeks?
7. The farmer gave his new son the name Marcus.
8. The head of the river was far away in Germany.
9. The king's son was the commander of the kingdom's forces.
10. My sister, give my gift to our mother tomorrow.

Find an English word that may be derived from each word in the vocabulary. Also, give the number of the rule above (1-4) that makes that word an I-stem.

Now we've covered the third declension. Next lesson, back to verbs. We've covered three declensions now, but only one conjugation, so it's time to start on the second.

• mare latum - wide sea, third declension I-stem noun, second declension adjective

• mons albus - white mountain, third declension I-stem noun, second declension adjective

• navis nova - new ship, third declension I-stem noun, first declension adjective

(By the way, notice how adjectives help narrow down the case? “Navis” could be nominative or genitive, and “novae” could be genitive or dative singular or nominative plural, but “navis novae” together can only be genitive singular. When translating, that kind of context can help us put the pieces together.)

1. Animalia in navem in flumine ambulaverunt. - The animals walked into the ship on the river.
2. Cives mei, laudate Deum. - Praise God, my fellow citizens.
3. Gens nostra in finibus Germanorum habitabunt. - Our clan will live in the territory of the Germans.
4. Castra hostium telis et igne oppugnavimus. - We attacked the camp of the enemy with weapons and fire.
5. Nauta trans mare magna cum audacia navigavit. - The sailor sailed across the sea with great boldness.
6. Servi panem viris et feminis dant et frumentum animalibus. - The slaves are giving bread to the men and women, and grain to the animals.
7. Pueri a parvo oppido ad magnam urbem ante bellum ambulaverant. - The boys had walked from the small town to the big city before the war.
8. Oppugnavi inimicum meum gladio; vulnera erant multa et magna. - I attacked my enemy with a sword; the wounds were many and great.
9. Ambulate, pueri, sub montem, et exspectate ibi signum belli. - Boys, walk up to the mountain and wait there for the signal of war.
10. Equus albus magnus in ponte stabat. - A large white horse was standing on the bridge.

1. Why did the enemy attack our little town with fire? - Cur hostes oppidum parvum nostrum igne oppugnaverunt?
2. The Roman people are our allies, aren't they? - Nonne populus Romanus sunt socius noster?
3. Many citizens praised the death of the bad consul. - Multi cives mortem consulis mali laudaverunt.
4. Our journey across the sea was long. - Iter noster trans mare erat longum.
5. After Caesar's death, there were many new poems about (his) reign. - Post mortem Caesaris, erant multa et nova carmina de regno.
6. Shall we seize the territory of the Greeks? - Occupabimusne fines Graecorum?
7. The farmer gave (his) new son the name Marcus. - Agricola filio novo nomen Marcum dedit.
8. The head of the river was far away in Germany. - Caput fluminis erat longe in Germania.
9. The king's son was the commander of the kingdom's forces. - Filius regis erat imperator copiarum regni.
10. My sister, give my gift to our mother tomorrow. - Da, soror mea, donum meum matri nostrae cras.

• animal, animālis, n., animal - animal, 4
• caedēs, caedis, f., murder - ??, 1
• cīvis, cīvis, m. or f., citizen - civil, 1
• fīnis, fīnis, m., end, boundary; (plural) territory - final, 1
• gēns, gentis, f., family, clan, tribe - genetics, 2
• hostis, hostis, m., enemy - hostile, 1
• ignis, ignis, m., fire - ignite, 1
• īnfans, īnfantis, m., baby - infant, 2
• mare, maris, n., sea - maritime, 4
• mōns, montis, m., mountain, hill - mountain, 2
• mors, mortis, f., death - mortal, 2
• nāvis, nāvis, f., ship - navy, 1
• nox, noctis, f., night - nocturnal, 3
• pānis, pānis, m., bread - pancakes (probably not really), 1
• pōns, pontis, m., bridge - pontoon (maybe sort of), 2
• urbs, urbis, f., city - urban, 3