zahllos
countless
So numerous that one cannot count them; innumerable.
Am Nachthimmel funkelten zahllose Sterne.
Countless stars sparkled in the night sky.

countless
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countless
So numerous that one cannot count them; innumerable.
Am Nachthimmel funkelten zahllose Sterne.
Countless stars sparkled in the night sky.

The word is made up of 'Zahl' (number) and the ending '-los' (-less). The ending '-los' means 'without,' so literally 'without number'—so many that one can no longer count them.
Es gibt zahllose Gründe, warum das Projekt scheiterte.
There are countless reasons why the project failed.
'Zahllos' (countless) is often used to describe a very large, overwhelming quantity. Common combinations are 'zahllose Beispiele' (countless examples), 'zahllose Möglichkeiten' (countless possibilities), or 'zahllose Male' (countless times).
Ich habe es dir schon zahllose Male erklärt.
I have explained it to you countless times already.
'Zahllos' (countless) is often used in written language or elevated language to emphasize a large quantity. It often sounds stronger and more poetic than other expressions.
Die Küste war mit zahllosen Muscheln bedeckt.
The coast was covered with countless shells.
little / few
'wenig' and 'zahllos' both describe a quantity, but they are strong opposites. 'wenig' means that only a small amount or number is present. 'zahllos' means that there are very many—so many that one can hardly count them, or cannot count them at all. 'wenig' is neutral and suitable for everyday use. 'zahllos' sounds stronger and is especially fitting when you want to emphasize a very large number.

Im Sommer sieht man am See zahllose kleine Mücken.
In summer, you can see countless little mosquitoes by the lake.
Für den Termin bleibt mir heute nur wenig Zeit.
I only have a little time left for the appointment today.