What does posterior mean?
Posterior is a formal word with two principal uses. As an adjective, it can mean occurring later in time or arranged behind something else: a posterior section comes after an earlier one, while a posterior part lies at the back. In anatomical and spatial contexts, it identifies the rear of the body or a structure opposite the front. The related noun refers especially to the buttocks, though the anatomical term “posterior surface” is broader and can describe any backward-facing part of a structure. Posterior also has an important technical role in statistics, where it refers to a probability revised in response to observed evidence. The word’s formal register suits academic, scientific, and technical writing more than ordinary conversation, where “back,” “later,” or “rear” are often more natural.
Occurring later in time; following something else. Also, situated behind or at the back of something.
"The decision was based on information posterior to the initial assessment."
Formal or technical. In anatomy, it means toward the back of the body and is commonly contrasted with “anterior.”
The rear of the body, especially the buttocks; also, a probability calculated using evidence observed after an initial estimate.
"The clinician examined the posterior and the muscles of the lower back."
As a body reference, it is formal and may sound clinical. In statistics, it is technical and normally appears in phrases such as “posterior probability.”
Normally used in the anatomical sense, especially for the buttocks; “posteriors” is more informal and can sound humorous or euphemistic.
"The diver landed awkwardly and injured one of her posteriors."
The word posterior comes from the Latin for “after,” the same root behind postage and postfix—and even the ordinary prefix meaning “after.”
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does posterior come from?
Posterior comes through English from the Latin posterior, meaning “after” or “later,” a comparative form of post, “after.” The same Latin root underlies words such as post, postage, and postfix. In English, posterior developed meanings relating both to what comes after in time and to what is behind in position.
Related word forms
How posterior is actually used
In general use, “posterior” is formal and often contrasts with “anterior.” In anatomy, it is a technical directional term meaning toward the back of the body. In statistics, “posterior” is a noun meaning a probability updated after examining evidence; “posterior probability” is the standard technical phrase.
Easily confused with posterior
Posterior means later or situated behind, whereas posterity refers to future generations.