Learn Croatian: Razgovaram s vjernim slugom. - I am talking with the loyal servant.

Even though sluga (servant) ends in -a and gets the feminine instrumental ending -om, it is grammatically a masculine noun because it refers to a male. Therefore, adjectives attached to it must use masculine endings. The masculine singular instrumental ending for this adjective is -im, giving us vjernim slugom.

Does sluga also take masculine adjectives in the plural?

This is a tricky rule! Nouns like sluga and kolega take masculine adjectives in the singular. However, in the plural, they switch to taking feminine adjective endings. So 'loyal servants' as a subject (nominative case) would be vjerne sluge, matching the feminine plural pattern.

Why is the phrase s vjernim slugom in the instrumental case?

The verb razgovarati (to talk / converse) pairs with the preposition s (with) to show who you are interacting with. When the preposition s means 'with' in the sense of company or interaction, it always requires the instrumental case.

Why do we use the short preposition s here instead of sa?