preposition
within, inside
B1
Innerhalb is a preposition meaning 'within' or 'inside', usually governing the genitive (innerhalb des Hauses). It can also be followed by a time expression ('within an hour'). In colloquial speech speakers sometimes use the dative, but standard German requires genitive for formal writing.
Examples
Innerhalb einer Stunde komme ich zurück.
I'll be back within an hour.
Innerhalb des Hauses ist es warm.
It's warm inside the house.
Innerhalb eines Monats kündigte die Firma mehrere Verträge, obwohl die Projekte noch nicht abgeschlossen waren.
Within a month the company terminated several contracts, although the projects were not yet completed.
Details
Mnemonics
Picture a clock with an inner circle marked 'innerhalb' indicating a time window.
Think 'inner + half' -> within a half/inside something.
Notes
Innerhalb is commonly used with the genitive to specify time or space ('innerhalb einer Woche', 'innerhalb des Gartens').