What is a prefix for the word night?

There isn't a common, single-word prefix specifically for "night". However, there are some prefixes that can be used to modify the meaning of "night" in specific contexts:

* Mid-: This prefix means "in the middle of," so "midnight" refers to the middle of the night.

* Over-: This prefix suggests excess or more than usual, so "overnight" means lasting through the night.

* Night-: This is more of a combining form than a prefix, used to create compound words like "nightfall" or "nightshade."

There are also prefixes that can be used to create words related to night, like:

* Noct-: This prefix means "night" and is used in words like "nocturnal" and "noctilucent."

* Nyc-: This prefix also means "night" and is found in words like "nyctalopia" (night blindness).

Ultimately, the best prefix to use will depend on the specific meaning you want to convey.