According to Webster's New World Dictionary and Thesaurus, stress is a physical, chemical, or emotional factor that causes bodily or mental tension and may be a factor in disease causation. Synonyms for stress include strain, pressure, and tension.

A definition of stress commonly used in the field of stress management is the body's response to any change to which it must adapt.*

*Source: Davis, M., Eshelman, E.R., & McKay, M. (2000). The relaxation and stress reduction workbook (5th ed.). Oakland, CA: New Harbinger Publications.