The Indefinite Suffix: -нибудь
While the suffix -то is used for things that are specific but unknown, the suffix -нибудь is used for things that are completely non-specific or hypothetical. You use -нибудь when "any" person, thing, or place will do. Because of this, it is frequently used in questions, offers, and plans for the future.
Кто-нибудь and Что-нибудь
Adding -нибудь to кто (who) creates кто-нибудь (anyone/someone). Adding it to что (what) creates что-нибудь (anything/something).
Какой-нибудь: Any kind of
To say "any" or "some kind of" before a noun, use какой-нибудь. Just like a normal adjective, the какой part changes its gender, number, and case to match the noun it describes, while the -нибудь ending stays exactly the same.
Где-нибудь and Куда-нибудь: Anywhere
As always, Russian distinguishes between location and motion. Their indefinite forms work the same way:
- где-нибудь means "anywhere" or "somewhere" (where an action happens).
- куда-нибудь means "anywhere" or "somewhere" (the destination of a movement).
Когда-нибудь and Как-нибудь
Adding -нибудь to когда (when) creates когда-нибудь. In questions, this usually translates to "ever," and in statements, "sometime" in the future.
Similarly, как-нибудь (from как) means "somehow" or "sometime" (in a non-specific way).
Declining Words with -нибудь
Remember that the base words like кто and что still decline for case, even when they have a suffix attached. The suffix simply tags along at the end. For example, if you need the accusative case of кто-нибудь, it becomes кого-нибудь.