How well a thing is made, judged against what it is for. Quality is not a property; it is a relation to a purpose.
Latin qualitas (a particular character, a property), from qualis (of what kind, such as); quality was first a question — of what kind? — before it became a judgment of how good.
How well a thing is made, judged against what it is for. The root's question — of what kind — is still underneath: quality is never absolute, it is always quality of something, for something.