- (physics) A quantity analogous to electrical impedance in some other energy domain
- (by analogy, software engineering, usually with “mismatch”) a measure of the opposition caused by differences between two paradigms, especially between object-oriented development and relational databases
- (physics) A measure of the opposition to the flow of an alternating current in a circuit; the aggregation of its resistance, and inductive and capacitive reactances; the ratio of voltage to current treated as complex quantities.
- (physics, usually with “acoustic” or “sound”) the ratio of sound pressure to volume flow rate treated as complex quantities.
- (physics, usually with “mechanical”) a measure of opposition to motion of something subjected to a force; the ratio of force to velocity treated as complex quantities.