I like the suggestion in namespace aliasing in https://stuartsierra.com/2015/05/10/clojure-namespace-aliase...:

As a general first rule, make the alias the same as the namespace name with the leading parts removed.

  (ns com.example.application
    (:require
     [clojure.java.io :as io]
     [clojure.string :as string]))

Keep enough trailing parts to make each alias unique. Did you know that namespace aliases can have dots in them?

  [clojure.data.xml :as data.xml]
  [clojure.xml :as xml]

Eliminate redundant words such as “core” and “clj” in aliases.

  [clj-http :as http]
  [clj-time.core :as time]
  [clj-time.format :as time.format]

Then you can see immediately what `d` is...

Namely:

  (require '[dk.ative.docjure.spreadsheet :as spreadsheet])

(You would still not know the library and might have to ask the same question, but it makes more sense.)

About `d`:

There are always exceptions. For example, some namespaces have established conventions for aliases:

  [datomic.api :as d]