Third declension: the hidden stem
With rēx, mīles and corpus the nominative hides the stem. The genitive in -is shows it: rēg-is. Then fixed endings follow.
Why
You see rēgem in a text and look under rēg- in your word list. Nothing. How do you find the word?
In the third declension the nominative often looks unlike the other forms. Rēx becomes rēgis, mīles becomes mīlitis, corpus becomes corporis. If you only know the nominative, you will not recognise the other forms.
That is why you always learn the genitive too. It shows the real stem, and from there everything follows one fixed row of endings. So you find rēgem under rēx, the king, and mīlitēs under mīles, the soldier. Many words from the Roman world belong here: king, soldier, father, city, ship.
See it
Pick rēx, mīles, corpus or cīvis. The nominative hides the stem, the genitive reveals it: the stem lights up, then the endings click on.
Description of the picture
At the top four buttons: rex, miles, corpus and civis. With rex you first see the nominative rex in large letters, the stem half hidden behind a curtain. Next to it the genitive regis slides in; the letters reg light up as the stem and the ending is gets its own colour. Then a table appears in which the stem reg comes back each time with the endings of the third declension: regi, regem, rege, and in the plural reges, regum, regibus. With miles the stem milit appears, with corpus the stem corpor, with the nominative and accusative the same and a plural in a. With civis the stem is civ and the genitive plural ends in ium.
Get it
In the third declension the nominative singular is the odd one out. Sometimes a letter has been added or lost: rēx is really rēg-s, mīles belongs to mīlit-. The genitive singular, always in -is, shows the real stem.
Take -is off the genitive and you have the stem: rēg-is gives rēg-, corpor-is gives corpor-. After that stem come the endings: -is, -ī, -em, -e in the singular, and -ēs, -um, -ibus, -ēs, -ibus in the plural.
Neuter words like corpus, nōmen and tempus follow the same rule as in the second declension: the nominative and accusative are the same, and the plural ends in -a: corpora, nōmina.
One group of words has -ium in the genitive plural: the i-stems, like cīvis (cīvium), urbs (urbium) and nāvis (nāvium). Your word list tells you.
Stem = genitive minus -is. Singular: the nominative on its own, then -is, -ī, -em, -e. Plural: -ēs, -um, -ibus, -ēs, -ibus. Neuter: nominative = accusative, plural -a. i-stems: genitive plural -ium.
Examples
rēx, rēgis
The genitive shows the stem rēg-: king.
rēgem
Accusative singular: the king as direct object.
mīlitēs
Nominative or accusative plural of mīles: the soldiers.
corpora
Neuter plural of corpus: the bodies.
cīvium
i-stem: genitive plural of cīvis, of the citizens.
patribus
Dative or ablative plural of pater: to the fathers or by the fathers.
Worked example
Make the dative singular of mīles, mīlitis (m.).
The genitive mīlitis ends in -is: third declension.
Take off -is: the stem is mīlit-.
The dative singular is -ī: mīlit + ī.
- Answer
mīlitī
Do it
Choose a level. You get a new exercise each time, checked straight away.
Pitfalls
Wrong: The accusative of rēx is rēxem.
The ending goes after the stem, not after the nominative. You get the stem from the genitive rēgis.
Right: rēgem
Wrong: Corpus is second declension, it ends in -us after all.
Look at the genitive: corporis ends in -is. It is a neuter word of the third declension.
Right: corpus, corporis (n.), plural corpora.
Wrong: Rēgēs is always the subject.
In the third declension the nominative and accusative plural both end in -ēs. The sentence decides.
Right: Mīlitēs rēgēs vident: the verb and the meaning tell you who sees whom.
In real life
- Our words come from the stem, not from the nominative: corpor- in corporation, nōmin- in nominate, tempor- in temporary.
- Corpus is an English word too: a body of texts collected for study.
- The plural tempora is in the famous cry O tempora, o mōrēs, a complaint about the times and the customs.
History
The cry O tempora, o mōrēs is found in Cicero's speeches against Catiline. There Cicero complains about his own time.
At the table
Play Stem Detective. A parent names an English word like military, corporation or nominate. The child finds the Latin stem in it (mīlit-, corpor-, nōmin-) and says the Latin word in the nominative. A right stem is one point, the right word another.
Something to do or talk about together, for parents and children. Mistakes are welcome.