What is the collective noun for doubt?

There isn't a widely accepted collective noun specifically for doubt.

While we can use "a cloud of doubt" or "a shadow of doubt," these are more metaphorical expressions than specific collective nouns.

If you're looking for a word to describe a collection of doubts, you could use:

* A swarm of doubts (evokes a sense of uncertainty)

* A murmur of doubts (suggests a growing unease)

* A torrent of doubts (implies a strong and overwhelming feeling)

Ultimately, the best word will depend on the context and the specific nuance you want to convey.