Conceptual stretching means dropping necessary defining attributes.

Evidence

More specifically, and more accurately, we can increase the extension by reducing the number of necessary attributes in the intension. “Conceptual stretching” thus means in operational terms eliminating necessary dimensions. — Gary Goertz, Social Science Concepts and Measurement, 1416

Categorization

• DEFINE: Gives ‘conceptual stretching’ a precise operational meaning: deleting necessary dimensions from the intension.
• XREF: Directly qualifies prior notes on comparative-concept breadth by tying breadth to the count of necessary attributes.