Condition is a versatile English word used as a noun and a verb to describe a state, requirement, or process. As a noun it commonly refers to the state or quality of something (for example an item's physical condition), a medical or health issue, a stipulation in an agreement, or a logical requirement. As a verb it means to prepare, treat, or influence something so it attains a desired state (for example to condition hair or to condition material).
Common senses
- State or quality: describes how something is — e.g. weather conditions, working conditions, or the condition of a used object.
- Medical condition: a health-related state or diagnosis, which may be chronic, temporary, or managed rather than strictly a disease.
- Contractual/legal condition: a clause that must be satisfied for an agreement or obligation to take effect.
- Logical and mathematical use: a requirement that makes a statement true (necessary or sufficient conditions).
- Probability and statistics: conditioning means restricting attention to cases where some event is known to hold (the probability of A given B).
- Psychological conditioning: learning processes such as classical and operant conditioning that change behavior through association or consequence.
- Material treatment (verb): to subject a substance to a process that alters its properties (e.g., conditioning skin, hair, or textiles).
In logic and mathematics, discussion of conditions often distinguishes between necessary conditions (without which a result cannot hold) and sufficient conditions (which guarantee the result). In programming and software engineering, preconditions and postconditions describe required inputs and expected outcomes for routines; conditional statements control flow based on boolean tests.
History and usage
The word derives from Latin roots associated with agreement and stipulation and entered English with senses related to terms and states. Over time it broadened to cover medical status, environmental states, and processes that change state. Today it is widely used across disciplines — law, medicine, computer science, psychology, everyday speech — each applying the core idea of a state or requirement to its domain.
Notable distinctions include the difference between a "condition" and a "disease" in medicine (a condition may be less specific or not strictly pathological), and between a "condition" and a "state" in everyday language (a condition often implies factors or requirements that affect change). Understanding necessary versus sufficient conditions also helps clarify arguments in reasoning and design.