magnus, a, um

indicating… magnus (masculine), magna (feminine), magnum (neuter)

They borrow endings from nouns. What noun declension is mostly masculine? Second declension, therefore the second declension noun endings are used to decline masculine adjectives. What noun declension is mostly feminine? First declension, therefore first declension endings are used. Now we see why these are called the 1st&2nd declension adjectives. 2nd Declension nouns also have a neuter endings so those neuter endings are borrowed for Adjectives.

You can find a chart of magnus, a, um fully declined in your Henle Latin Grammar on page 14, grammar entry number 72.

Here is a chart of endings for the 1st & 2nd declension Adjectives:

The next adjective family is adjectives of the 3rd declension. They appear like this…

gravis, e

indicating… gravis (masculine), gravis (feminine), grave (neuter)

They borrow some endings from 3rd declension nouns, but do not follow them exactly. You can find a chart of gravis, e fully declined in your Henle Latin Grammar on page 16, grammar entry number 78,

Here is a chart of endings for 3rd declension Adjectives:

Adjectives must agree with the nouns they modify in Gender, Number, and Case.

Therefore you must identify the G, N, C of the noun you wish to modify before you can determine which ending to use to have your adjective agree. It is important to use the term “agree” here rather than “match” because you might be tempted to think that the endings will “match” or be identical. Sometimes they are identical, but often they are not.

Add in this other consideration…

Adjectives of QUANTITY generally

PRECEED the noun they modify

and

Adjectives of QUALITY generally

FOLLOW the nouns they modify

And you can see how adjective use may require some practice.

Check out my Adjective Practice Game digital download in the SHOP. This game practices with nouns from Henle FYL Unit 1 and Adjectives from Unit 2. You will receive instructions for play and examples, helpful adjective charts, master lists of nouns and adjectives, printable noun and adjective cards to cut out, and a set of three printable dice to cut out and fold.