Learn Finnish: Johtokunta nimitti hänet eilen varapuheenjohtajaksi. - The board of directors appointed him as the vice chairperson yesterday.

The verb nimittää (to appoint) requires the role or title to be in the translative case, which ends in -ksi. This case is used because the person is transitioning into a new state or position. You will see this same rule with verbs like valita (to elect) and kutsua (to call or name).

I sometimes mix up the essive (-na) and translative (-ksi) cases for roles. Why couldn't we use the essive varapuheenjohtajana here?

The essive case (-na) is used when someone is already acting in an ongoing role, for example to say 'As vice chairperson, he voted...'. The translative (-ksi) is required here because the sentence describes the actual transition or change into that role. Verbs of appointing and electing always trigger this change-of-state case.

Why is the object hänet instead of the partitive häntä?

The act of appointing is a completed action, which means the verb takes a total object rather than a partitive one. For personal pronouns like hän, the total object uses the special accusative form that ends in -t, making it hänet.

What are the component parts of the word varapuheenjohtajaksi?