Today's introit is taken partly from St Paul's letter to the Philippians, chapter 2, along with a verse from Psalm 8.
In nomine Jesu omne genu flectatur, coelestium, terrestrium, et infernorum: et omnis lingua confiteatur, quia Dominus Jesus Christus in gloria est Dei Patris. * Domine Dominus noster: quam admirabile est nomen tuum in universa terra!
In the Name of Jesus let every knee bow, of those that are in heaven, on earth, and under the earth: and let every tongue confess that the Lord Jesus Christ is in the glory of God the Father. * O Lord our Lord: how admirable is Thy Name in the whole earth!
In - In. Preposition which is followed by the ablative when it indicates fixed state or location.
nomine - the name. Name is nomen. Ablative case here, following in.
Jesu - Of Jesus. Genitive case. Jesus is treated as a 4th declension noun, with genitive Jesu, showing possession.
omne - all. The ending is neuter, to go with genu.
genu - knee. Subject of the verb flectatur. Nominative case.
flectatur - may it bend. The verb is flecto/flectere/flexi/flectum - to bend. Here with have a passive subjunctive. Passive since something is being done to the knee; subjunctive since it is a wish or desire.
coelestium - of things in heaven. Genitive plural of coelestis - something heavenly.
terrestrium - of things on earth. Genitive plural of terrestris - something earthly.
et - and.
infernorum - of things in the underworld. Genitive plural of infernus, something of the underworld.
et - and.
omnis - All. Ending is in agreement with lingua, which it modifies.
lingua - Tongue. Subject of the verb confiteatur.
confiteatur - may it confess. The verb is confiteor/confiteri/confessus - to confess or acknowledge. We have here a subjunctive, expressing desire or wish.
quia - since
Dominus - the Lord. Subject of the verb est.
Jesus - Jesus. Nominative, to go with Dominus.
Christus - Christ. Nominative, to go with Dominus.
in - in
gloria - the glory. Ablative case to follow in.
est - is.
Dei - of God. Genitive case.
Patris - of the Father. Genitive case.
Domine - O Lord! Vocative case.
Dominus - Lord
noster - our. Modifies Dominus.
quam - how
admirabile - admirable. The ending is neuter, to go with nomen, which it modifies.
est - is.
nomen - name. Nominative case, as the complement of the verb est.
tuum - your/thy. Modifies nomen.
in - in.
universa - the whole. Adjective modifying terra. In the ablative to agree with terra.
terra - the earth. Ablative case to follow in.
1. Gender of Nouns.
Latin nouns have a gender - masculine, feminine, or neuter. (A small number are common, i.e. can be either). Some are obvious, e.g. names of men are masculine, and of women feminine, but otherwise it isn't usually obvious.
There are trends, as these schoolboy rhymes indicate:
"A Man, a name of People, and a Wind,
River or Mountain, Masculine we find."
"A Woman, Island, Country, Tree,
and City, Feminine we see."
You can always find the gender if you need it from a dictionary. The main use I want to highlight now, is that when a noun is modified by an adjective, the ending of the adjective changes according to the gender of the noun.
2. Agreement of Adjectives.
The ending of adjectives modifies according to the case, number, and gender of its noun.
In today's introit we have:
omne genu - every knee. Genu (knee) is neuter (and singular and nominative)
omnis lingua - every tongue. Lingua (tongue) is feminine (and singular and nominative).
Consider the following different forms of omnis (every):
Omnis homo amat Deum - every man loves God. (Masculine, singular, nominative)
Deus amat omnem hominem - God loves every man. (Masculine, singular, accusative)
Deus amatur omnibus hominibus - God is loved by all men. (Masculine, plural, ablative)
Omnes pueri ab amant libros - All boys love books. (Masculine, plural, nominative)
Libri amantur ab omnibus pueris - Books are loved by all boys. (Masculine, plural, ablative)
Petrus amat omnia animalia - Peter loves all animals. (Neuter, plural, accusative)
3. Declension of nouns. (1st and 2nd)
There are five basic patterns followed by the endings of nouns, which are called the five declensions. Some are irregular, either in some cases only or entirely.
The first two, which are very common, are as follows.
i) First declension for nouns ending in -a (usually feminine)
Nominative singular: ecclesia (church)
Vocative singular: ecclesia
Accusative singular: ecclesiam
Genitive singular: ecclesiae
Dative singular: ecclesiae
Ablative singular: ecclesia
Nominative plural: ecclesiae
Vocative plural: ecclesiae
Accusative plural: ecclesias
Genitive plural: ecclesiarum
Dative plural: ecclesiis
Ablative plural: ecclesiis
ii) Second declension for nouns ending in -us (usually masculine)
Nominative singular: dominus (lord)
Vocative singular: domine
Accusative singular: dominum
Genitive singular: domini
Dative singular: domino
Ablative singular: domino
Nominative plural: domini
Vocative plural: domini
Accusative plural: dominos
Genitive plural: dominorum
Dative plural: dominis
Ablative plural: dominis
iii) Second declension for neuter nouns ending in -um
(Notice that the first three cases are the same: -um in singular or -a in plural. Otherwise, it follows the pattern of dominus)
Nominative singular: bellum (war)
Vocative singular: bellum
Accusative singular: bellum
Genitive singular: belli
Dative singular: bello
Ablative singular: bello
Nominative plural: bella
Vocative plural: bella
Accusative plural: bella
Genitive plural: bellorum
Dative plural: bellis
Ablative plural: bellis