Latin Reference — Vol. III.b: Possessive Words
The second interstitial, paired with III.a. Possessives — my, your, our — are adjectives, so they obey Vol. III’s three-way rule (case, number, gender). The only genuinely new idea here is whose: Latin marks the owner more precisely than English does.
The five possessives
| Word | Means | Owner |
|---|---|---|
| meus, mea, meum | my | I (one) |
| tuus, tua, tuum | your | you (one person) |
| suus, sua, suum | his/her/its/their own | the subject (reflexive) |
| noster, nostra, nostrum | our | we |
| vester, vestra, vestrum | your | you (several people) |
Two things English can’t see but Latin insists on:
Singular vs plural “your”. English lost this (we once had thy vs your). Latin keeps it sharp: tuus = belonging to one person, vester = belonging to a group. So canis tuus is one owner’s dog; canis vester is the dog of you-several. The pair tracks the pronouns tū (you-one) and vōs (you-many).
Aside — Pater noster, Pater vester. The Lord’s Prayer opens Pater noster — “our father” — which is why it’s nicknamed the Paternoster. Change the possessive and you get Pater vester, “your (pl.) father”, a phrase that also appears in the Latin gospels. The same -ster word you meet in a Duolingo dog sentence carved the name of a prayer.
The reflexive suus. Suus means specifically the subject’s own. Canem suum amat — “she loves her own dog”. If the dog belonged to someone else in the sentence, Latin switches to eius (the genitive of is/ea/id, from III.a): canem eius amat — “she loves his/her [someone else’s] dog”. A distinction English blurs with a plain “her”.
They decline — beware the lookalikes
Because possessives are adjectives, they throw off the full set of endings — and these are exactly the forms that get mistaken for different words. tuī, tuō, tuam are not separate vocabulary; they are tuus in other cases.
meus and tuus decline like magnus (Vol. III) — first/second declension:
| Case | M sing | F sing | N sing |
|---|---|---|---|
| Nom | meus | mea | meum |
| Gen | meī | meae | meī |
| Dat | meō | meae | meō |
| Acc | meum | meam | meum |
| Abl | meō | meā | meō |
(noster and vester follow the same pattern but drop the -e- in most forms: noster, nostra, nostrum; gen nostrī, nostrae, nostrī. Like magnus with a syncopated stem.)
So when you saw tuō earlier in your learning, nothing exotic was happening: it’s tuus in the dative or ablative singular — “to/with your —”. Two axes are working at once: whose (the tu-/vester- choice) and which case (the Vol. I endings). They wear similar tails, which is why they tangle.
Worked examples
| Latin | Translation | Mechanics |
|---|---|---|
| Canis tuus dormit. | Your (one person’s) dog sleeps. | tuus: nom m sing, agreeing with canis |
| Canis vester in culinā dormit. | Your (you-all’s) dog sleeps in the kitchen. | vester: plural owner; in + abl (location) |
| Mātrem meam amō. | I love my mother. | meam: acc f sing — agrees with mātrem, not with “I” |
| Cum amīcō tuō venit. | He comes with your friend. | tuō: abl m sing after cum |
| Fīlia sua eum nōn videt. | His own daughter does not see him. | sua: reflexive, daughter belongs to the subject; eum: object, someone else |
| Nōmen canis vestrī scio. | I know the name of your dog. | vestrī: gen m sing — “of your dog” |
Note the trap in mātrem meam: the possessive agrees with the thing owned (mother — feminine, accusative), never with the owner (I). English speakers instinctively want it to echo the owner; Latin never does.
The drill
Take any noun you’ve drilled and run meus through it in two cases, then swap to tuus, then vester — canis meus, canem meum; canis tuus, canem tuum; canis vester, canem vestrum. Hear how the ending (case) and the stem (whose) move independently. Then test the reflexive: say “she loves her own dog” (suum) and “she loves her dog” — someone else’s — (eius), and feel Latin make a distinction English can’t.