Masculine nouns ending in '-a'
In Italian, a noun ending in -a is usually a strong signal that the word is feminine. However, there is a well-known group of words that break this rule completely. These words end in -a but are actually masculine.
This quirk often catches learners off guard because the natural instinct is to pair an -a ending with feminine articles and adjectives. If you have ever caught yourself saying la problema instead of il problema, you have encountered this exception first-hand.
A large portion of these masculine exceptions end in -ma and come from ancient Greek. Very common words like problema, sistema, and programma fall into this category.
Because they are masculine, you must use masculine articles like il and un. Any adjectives you attach to them must also agree in the masculine form.
The -ma ending is not the only culprit. A handful of other important nouns also end in -a while remaining strictly masculine. These include words related to professions or historical roles, like poeta, profeta, and papa, as well as everyday words like pianeta and pigiama.
When you make these masculine nouns plural, they follow the standard masculine rule: the final -a changes to -i. The articles and adjectives must change to their masculine plural forms as well.
This means il problema becomes i problemi, and il poeta becomes i poeti.
Remember that a specific group of nouns ending in -a, especially those ending in -ma, are masculine. Always use masculine articles and adjectives with them, and change their ending to -i in the plural.