If electron density at a particular point in a molecule is higher or lower than what you'd expect from a single Lewis structure, and various canonical structures can be drawn to show how electron [..]

This is the term most commonly used to describe the influence (on reactivity, spectra, etc.) of a substituent through electron delocalization into or from the substituent. The use of the term obviates the need to attempt to distinguish between the operation of the mesomeric effect and the electromeric effect. (An alternative term with essentially t [..]