n. restraint; framework; raised edge of a sidewalk

'Curb' has multiple related meanings fitting the definition. It refers to the raised edge of a sidewalk (a physical restraint/framework for vehicles), and also the act of restraining or limiting something (as in 'curb your enthusiasm'). 'Ken' means knowledge or range of vision, 'predilection' is a preference, and 'equanimity' means mental calmness - none match the definition.