Learn Finnish: Minun veljeni pelasti tämän pienen lintusen.

It comes from the noun lintu (bird) plus the diminutive suffix -nen, creating lintunen (little/cute bird). Because it is the object of the completed action pelasti, it takes the accusative case (which ends in -n). As with all words ending in -nen, the stem changes to -se- before adding the ending, resulting in lintusen.

If lintunen already means "little bird," why does the sentence also use the adjective pienen?

While it might seem repetitive, this is very common in Finnish. The diminutive suffix -nen often adds an affectionate, endearing tone rather than just indicating literal size. Pairing it with pienen (small) emphasizes the bird's vulnerability and cuteness.

Why are tämän pienen lintusen in the accusative case instead of the partitive?

The verb pelasti (saved) implies a completed, successful action, so it takes a total object. If you used the partitive case (tätä pientä lintusta), it would mean the action was ongoing or incomplete, translating more like "was trying to save" or "was in the process of saving."

Why do we have both minun and the possessive suffix -ni in veljeni?