koilos

Koilos is a term of Greek origin, transliterated from the Ancient Greek κοῖλος, meaning hollow, cavity, or concavity. In classical Greek usage, it described physical hollowness and appears in various compounds and descriptions across ancient texts. The word has continued to influence modern scientific vocabulary through the formation of combining forms such as koilo- or koil-, which denote hollowness or cavity-like structures.

In medical terminology, the combining form koilo- (often anglicized as koil-) is used to indicate hollow or vacuolated features in biological tissues. A well-known example is koilocytosis, the cytopathic change seen in certain epithelial cells infected with human papillomavirus (HPV). Koilocytes exhibit perinuclear clearing, giving the appearance of a hollow or “empty” space around the nucleus, which reflects the Greek sense of hollowness embedded in the term.

Beyond medicine, koilos serves primarily as a productive root in compound terms rather than as a standalone English noun. It does not designate a specific modern entity or location in its own right, but it underpins terminology in disciplines that describe hollow or hollowed structures, cavities, or concavities. The etymological lineage traces back to Greek κοῖλος, with the sense of hollowness contributing to diverse technical terms in anatomy, pathology, and related fields.

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