Learn Hardcore Russian: Завершённый проект радует меня.

Завершённый is a past passive participle (причастие), but here it’s used like an adjective modifying проект. It literally means “that has been completed.” In Russian, participles can take adjective endings and agree in gender, number, and case with the noun they describe.

How do you form the participle завершённый from the verb завершить?

You start with the perfective infinitive завершить (to complete), drop -ть, and add the participle suffix -ённ- plus the adjective ending -ый. The steps are:

завершить → заверш(и) + ённ
завершённ + ый → завершённый
It then inflects like a regular adjective: завершённого, завершённому, завершённым, etc.

What’s the difference between завершить, закончить, and окончить?

All three mean “to finish/complete,” but their usage and nuance differ:

завершить – a bit more formal or technical (“to bring to an end,” often used in reports or project planning).
закончить – the most general everyday verb for “finish” or “end.”
окончить – often used with institutions (“окончить университет” – “to graduate from a university”) or formal processes.

Which cases are проект and меня, and why are they in those cases?