ἄδυτον

English (Autenrieth)

(δύνω, ‘not to be entered’): shrine, temple, ‘holy of holies.’

English (Slater)

ᾰδῠτον (v. l. ἄδυτος.)
   1 sacred place, sanctuary ὁ Χρυσοκόμας εὐώδεοσἐξ ἀδύτου εἶπε i. e. the temple of Delphic Apollo (O. 7.32) μαντευμάτων δὲ θεσπεσίων δοτῆρα καὶ τελεσσιε[πῆ] θεοῦ ἄδυτον[ (cf. Σ. (P. 11.5), πυκνῶς δὲ τίθησιν ὁ Πίνδαρος κατὰ τὸ ἀρσενικὸν τὸν ἄδυτον· [πῆ] supp. Wil.: [πες] Galiano: perhaps the oracle of Apollo Ptoios is meant.) Πα. . 3. ὦ Πάν, Ἀρκαδίας μεδέων καὶ σεμνῶν ἀδύτων φύλαξ (sc. μεγάλας Ματρός.) fr. 95. 2.

Russian (Dvoretsky)

ἄδῠτον: τό заповедное (священное) место, святилище Hom., Pind., Her., Eur., Plut., Luc.; τὸ ἄδυτον τῆς βίβλου Plat. самая сокровенная часть книги.

Middle Liddell

ἄδυτος as Subst., the innermost sanctuary, Il., etc.

Wikipedia EN

The adyton (Ancient Greek: ἄδῠτον [ádyton], 'innermost sanctuary, shrine', lit. 'not to be entered') or adytum (Latin) was a restricted area within the cella of a Greek or Roman temple. The adyton was frequently a small area at the farthest end of the cella from the entrance: at Delphi it measured just 9 by 12 feet (2.7 by 3.7 m). The adyton often would house the cult image of the deity.

Adyta were spaces reserved for oracles, priestesses, priests, or acolytes, and not for the general public. Adyta were found frequently associated with temples of Apollo, as at Didyma, Bassae, Clarus, Delos, and Delphi, although they were also said to have been natural phenomena (see the story of Nyx). Those sites often had been dedicated to deities whose worship preceded that of Apollo and may go back to prehistoric eras, such as Delphi, but who were supplanted by the time of Classical Greek culture.

In modern usage, the term is sometimes extended to similar spaces in other cultural contexts, as in Egyptian temples or the Western mystery school, Builders of the Adytum.

The term abaton (Koinē Greek: ἄβατον, [ábaton], 'inaccessible') or avato (Greek: άβατο, [ˈavato]) is used in the same sense in Greek Orthodox tradition, usually of the parts of monasteries accessible only to monks or only to male visitors.