>>82165945 (OP)
Concepts mean their referents
There is no external referent concept of 'chair', each human has their own individual concept of 'chair'
Definitions are a tool for standardizing concepts, they are not the meaning of the concept.
Concepts overlap. A chair can also be op's mom.
Edge cases are expected and don't need to have a universally agreed categorization. You are not clever for pointing them out nor do exceptions invalidate the rule.