Adverbs provide more information about the location, time, manner or reason why something is or happens.

Certain adverbs, such as "wo", "wann" and "wie" can be combined with the prefix "irgend-" to indicate a general, unspecified place, time or manner.

Examples:
Das war irgendwann im 6. Jahrhundert vor Christus. (The exact time is undefined or unknown.)
Können Sie mir sagen, ob es hier irgendwo ein Orakel gibt? (The precise location is not known.)
Das ist irgendwie unheimlich. (What's "unheimlich" about it is not clearly specified.)