Accusative case is also used for the objects of most of the Latin prepositions.
Here are the basic and very general rules for making a singular accusative:
- If a word ends in "-us", then the accusative ends in "-um". Tullius becomes Tullium.
- If a word ends in "-a", then the accusative ends in "-am". Livia becomes Liviam.
- If a word ends in "-o", then the accusative ends in "-onem". Cicero becomes Ciceronem.
- Many other words change their ending to "-em" whose rules are more difficult and are not detailed here. Here are some just for example:
- Audens in accusative becomes Audentem,
- Venus in accusative is Venerem,
- homo in accusative is hominem,
- praetor in accusative is praetorem,
- consul in accusative is consulem, and so on.
- Nouns of the neutral gender which often end in "-um" have no accusative different from nominative, so, for example forum is forum in accusative.
Accusative forms in all declensions
Attention: neuter nouns have no accusative form separate from their nominative. It means that all neuter nouns have accusatives identical to their nominatives, and, additionally, all neuter nouns have a plural nominative-accusative form that ends in -a, regardless to their declension group.
Also note that in the third declension, there are two subcategories: "consonant stem" and "i-stem". They are almost identical, but when it comes to the neuter plural accusative form, nouns of the "consonant stem" get an ending "-a", while "i-stem" nouns get an "-ia" ending. How to differentiate between "consonant stem" and "i-stem"?
Nouns of "i-stem" are the following:
- nouns ending in -is, -es, and having a genitive form with a number of syllables equal to their nominative form. E. g.: civis, civis mf, or collis, collis m;
- nouns ending in consonant + s (-rs, -ns, -ps, -bs, -x), but only, and exclusively only, if before their genitive ending -is there are at least two consonants. E. g.: gens, gentis, f ("-nt-" is two consonants before the "-is"), or nox, noctis f ("-ct-" is two consonants before the "-is").
- neuter nouns ending in -e, -al, -ar. E. g.: mare, maris; n, animal, -alis, n; nectar, nectaris, n.
- almost all adjectives of the third declension
Nouns of "consonant stem" are all nouns of the third declension not matching the requirements listed above.
|First declension||Second declension|
terra, -ae, f
tribúnus, -í, m
auspicium, -í, n
|Third declension||Fourth declension|
léx, légis, f
iús, iúris, n
cívis, -is, mf
mare, -is, n
senátus, -ús, m
cornú, -ús, n
diés, éí, m