
stundenlang
for hours
Continuing over a period of several hours.
Wir haben stundenlang über seine Zukunftspläne diskutiert.
We discussed his plans for the future for hours.
for hours
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for hours
Continuing over a period of several hours.
Wir haben stundenlang über seine Zukunftspläne diskutiert.
We discussed his plans for the future for hours.
The word is simply built from 'Stunden' (hours, plural of Stunde) and 'lang' (long). It literally means 'for the duration of hours.'
Die Reparatur des Autos dauerte stundenlang.
The repair of the car took hours.
The structure [unit of time] + 'lang' is very productive. Following the same pattern, you can also form 'tagelang' (for days), 'wochenlang' (for weeks), 'monatelang' (for months), and 'jahrelang' (for years).
Nach dem Sturm waren wir tagelang ohne Strom.
After the storm, we were without power for days.
As an adverb, 'stundenlang' (for hours) usually appears in the middle of the sentence to describe the duration of an action. It can also appear at the beginning of the sentence for emphasis; then the verb follows in second position.
Die Kinder haben stundenlang im Garten gespielt.
The children played in the garden for hours.
hour-long
Stundenlang and stündig both refer to a duration of several hours. Stundenlang usually describes an imprecise duration that is perceived as long, whereas stündig is almost always used with a number or numeral word to indicate a specific or limited duration. Use zweistündig for a precise duration; otherwise, stundenlang is often the better choice.

Die Sitzung dauerte stundenlang und schien kein Ende zu nehmen.
The meeting lasted for hours and seemed as though it would never end.
Die Sitzung war zweistündig und endete pünktlich um zwölf Uhr.
The meeting was two hours long and ended promptly at noon.