A measure of the inherent capacity for a system, machine, or software to be modified, re-engineered, or completely repurposed by the end-user. It is the antithesis of "proprietary" or "black-box" design.
In a person, it refers to a high-level cognitive state characterized by a
persistent "
train of thought" dedicated to tinkering,
troubleshooting, and seeking unconventional solutions—refusing to accept a design’s limitations as final.