Tacit

Tacit is an adjective meaning understood or implied without being stated. The word derives from the Latin tacitus, meaning silent, and has been used in English to describe understandings that are not spoken aloud or formally declared.

In philosophy and social theory, tacit knowledge refers to know-how and understanding that is difficult or impossible to articulate in words. Michael Polanyi popularized the concept, arguing that much knowledge resides in the mind and through practice rather than explicit instruction. Tacit knowledge is typically learned through immersion, observation, and doing, such as riding a bicycle or recognizing musical phrasing, where the skill is known but hard to describe in explicit terms.

Tacit is also used in legal and everyday contexts to describe consent or agreement inferred from conduct rather than explicit declaration. Tacit consent or tacit agreement arises when actions, inaction, or routine practice imply assent, such as using a service or remaining in a jurisdiction, even without a formal written or spoken agreement. Tacit rules refer to social norms and expectations that govern behavior without being codified.

In contrast to explicit, which is stated openly, tacit emphasizes the unspoken aspect of understanding. Although often used interchangeably with implicit in everyday language, tacit connotes an experiential, practitioner-based form of knowledge or consent that is not readily articulable.

See also: implicit knowledge, implicit consent, taciturn.