Differences between a library and a module in julia?

I’m mainly interested in the Base library in Julia. It looks like I can add my defined method as the following.

julia> import Base

julia> function Base.rand()
            println("my base")

I tried

help?> Base
search: Base basename AbstractSet Broadcast broadcast broadcast! AbstractString AbstractDisplay set_zero_subnormals get_zero_subnormals

  The base library of Julia.

So, Base is a library in Julia. For my understanding, a library is a bunch of modules together? Is this true?

I don’t believe that the word library as used here is a technical term. Base is a module.