Sigil

A sigil (/ˈsɪdʒɪl/[1]) is a type of symbol used in magic. The term has usually referred to a type of pictorial signature of a deity or spirit. In modern usage, especially in the context of chaos magick, sigil refers to a symbolic representation of the practitioner's desired outcome. https://en.wikipedia.org/wiki/Sigil

Sigil, a seal used to authenticate a document, a wrapper for one such as a modern envelope, or the cover of a container or package holding valuables or other objects https://en.wikipedia.org/wiki/Seal_(emblem)

An epub editor app. https://en.wikipedia.org/wiki/Sigil_(application)

• see Wiki-Ebook
• Feb'2014: At this point Sigil is no longer being actively developed... If you find it's not meeting your needs or if you want to see what else is out there I recommend checking out cailbre's editor.
  • not quite true? https://sigil-ebook.com/
  • broken by epub-3 changes?