D&D 5E Primeval Thule setting; What is a "rest"?

[Greenstone.Walker]

There is only one place in the manuals where a short or long rest is described, namely gathering poisons. The rest of the time, it just says "You regain this after a rest."

So, what does "a rest" mean? A short rest, a long rest, a short or long rest, or "it varies"?

 

[Tony Vargas]

Either a short or long rest will do.

 

[BookBarbarian]

If it doesn't specify between short or long, than i would assume it means both short and long rests. Since those are the only kinds of rests there are.