Sanctum sanctorum

The Latin phrase sanctum sanctorum is a translation of the Hebrew term קֹדֶשׁ הַקֳּדָשִׁים (Qṓḏeš HaQŏḏāšîm), literally meaning Holy of Holies, in Latin texts, this generally refers to the holiest place of the Ancient Israelites, inside the Tabernacle and later inside the Temple in Jerusalem.

The plural form sancta sanctorum is also used, arguably as a synecdoche, referring to the holy relics in the sanctuary.

[1] Hence, the derivative usage denotes the Sancta Sanctorum chapel in the complex of the Archbasilica of Saint John Lateran, Rome.

The Latin word sanctum is the neuter form of the adjective "holy," and sanctorum is its genitive plural.

Personnel in uniform — which in Germany includes student corporations — give the military salute when passing by or in the moment of elevation.