borrowed from Latin adytum,
borrowed from Greek ádyton,
neuter of ádytos
"not to be entered," from a- 2a-
verbal adjective of dýein
"to enter, make one's way into, sink," of uncertain origin
Supposed kinship of the Greek verb with a Sanskrit gerundive upādútyaḥ "to be put on (of a belt)" is apparently groundless, as the Sanskrit word should properly be read as "to be burnt" and hence belongs with Sanskrit dunóti "(s/he) burns," Homeric Greek dédēe "blazes up" (see Karl Hoffmann, "Materialen zum altindischen Verbum," Zeitschrift für vergleichende Sprachforschung, Band 79 , pp. 177-81). The Greek verb is thus deprived of any secure Indo-European comparisons, with the possible exception of Armenian enerk "immersed (something)."