motive
Adjective[C/U] Both
pl: motives
This word carries a heavy association with psychology and forensics. It describes the internal engine of human behavior, focusing on the hidden "why" behind an action rather than the action itself. It often implies a secret or calculated intention, particularly in legal or suspicious contexts. When used as an adjective, the word shifts from psychology to physics. It describes the raw force or energy required to trigger movement. This usage is significantly more formal and technical than the noun form, appearing mostly in engineering or historical texts regarding machinery.
Countable when referring to a specific reason for an action, such as a financial motive. Uncountable when referring to the general concept of human motivation.