宇称 (yǔ chēng) is a technical term in physics meaning 'parity'—a property describing how a physical system behaves under spatial inversion (i.e., flipping all spatial coordinates: x → −x, y → −y, z → −z). The character 宇 (yǔ) means 'universe' or 'space', evoking the three-dimensional spatial domain; 称 (chēng) means 'to measure', 'to appraise', or 'to call', suggesting a standard of evaluation. Together, 宇称 literally conveys 'spatial appraisal' or 'evaluation of spatial symmetry'.

This term appears primarily in quantum mechanics and particle physics—for example, when discussing whether a wavefunction remains unchanged (even parity) or flips sign (odd parity) under coordinate inversion. It’s essential for understanding conservation laws and symmetry-breaking phenomena, such as the famous violation of parity in weak nuclear interactions discovered by Lee and Yang in 1956. Learners will encounter it in advanced science texts, not in daily conversation.