Here are some possibilities, depending on the context:
1. Referring to a writing implement:
* It could refer to a quill pen made entirely from a bird's feather, without any additional modifications or additions. This would mean it hasn't been cut, shaped, or treated with ink in any way. This is very unlikely in practice, as quill pens are almost always prepared for writing.
2. Referring to a type of material:
* Quill is the name for the stiff, hollow shaft found in the wing and tail feathers of birds, particularly those of larger birds like geese and swans. "Pure quill" might refer to this material in its raw, unprocessed state, before any alterations are made.
3. Referring to something else entirely:
* It's possible the term "pure quill" is being used in a specific, specialized context like a particular brand of writing implement or a unique type of artwork.
To understand the meaning, you need more context.
Please provide more information about where you encountered this term.