FIFTH DECLENSION CASE ENDINGS N/V. -es Gen. -ei Dat. -ei Acc. -em Abl. -e N/V. -es Gen. -erum Dat. -ebus Acc. -es Abl. -ebusThe nominative singular is always "-es", which makes this declension much easier than the second and the third declensions, in which there are a variety of possible endings for the nominative singular. Therefore, a fifth declension noun will always end in "-es" -- and that is the first entry in the dictionary. But be careful not to make an elementary error in logic. All fifth declension nouns end in "-es" in the nominative singular, but not all nouns which end in "-es" in the nominative singular are fifth declension. "Nubes", for example, ends in "-es", but its genitive is "nubis", clearly telling you that it's a third, not a fifth declension noun. Be sure to check the nominative and the genitive forms for your nouns. A fifth declension noun will look like this: "x"es, -ei (gender).
By nature, the thematic vowel of the fifth declension is long, and it "wants" to stay long. Often, however, it becomes short when certain endings are attached. For "res", the thematic vowel "-e-" becomes short when you add the genitive and dative singular ending long "-i" (and it also is short before the "-m" ending of the accusative singular). But when the thematic vowel "-e-" is itself preceded by another vowel -- as it is in "dies" -- then it stays long before the genitive and dative ending long "-i". So you get "diei" for the genitive singular, not "dii". Since you're not overly concerned with getting all the long marks right at this point in your study, you might just as well cross out "dies" in Wheelock and forget about it. The stem of "dies" is "die-" to which you add the fifth declension case endings.
When the noun in this kind of construction is modified by an adjective, Latin has the option of droping the preposition "cum". So this sentence could also be written: "Id magna celeritate fecerunt". But if the noun governed by "cum" is not qualified by an adjective, the "cum" must be used. This is incorrect: "Id celeritate fecerunt"; but this is not: "Id cum celeritate fecit"; neither is this: "Id magna cum celeritate fecit"; nor this: "Id magna celeritate fecit".
One preposition which takes the ablative case requires some special caution, however, and that's "cum". Remember, "cum" means "with" in two different senses:
res, rei (f) Start by scratching off the first translation "thing". "Res" doesn't mean "thing" in our common sense of "What's that thing on the table"? or "Bring me that thing". It doesn't mean a non-descript object for which we can't quite come up with a name. It means "thing" when we say something like "What's this thing about you're not wanting to learn Latin"? or "Things sometimes get out of control". It means "matter", "affair", or "business" (non-commercial). res publica (f) First, this is the origin of our one word "republic", but in Latin it is two words -- the noun "res" and the adjective "publicus, -a, -um" modifying it. Therefore both "res" and "publica" decline: rei publicae rei publicae rem publicam re publica etc. Second, it obviously doesn't mean "public thing" as in "public object", but "public business or affair". Here you can see the real meaning of "res". medius, -a, -um It is an adjective, not a noun, so it can't be used the way our noun "middle" is used. We say "the middle of the city", putting "city" into the genitive case. Latin can't do this, because "medius" doesn't mean "middle", but "mid". Hence they say "medius urbs"; or "media nocte" ("in the middle of the night").01/18/93