سِرْدَابٌ, an arabicized word, (Ḳ,) from [the Pers.] سَرْدٌ [i. e. “cold”] and آبْ [“water”], (TA,) A subterranean structure, for the summer: (El-Aḥmar, Ḳ:) or a narrow place into which one enters: (Mṣb:) [applied in the present day to a cellar, or subterranean vault, in which anything is put to be kept cool:] pl. سَرَادِبُ (Mṣb) [or سَرَادِيبُ].

السِّرْدَابِيَّةُ A people of those who compose the extravagant zealots of the [sect called] رَافِضَة [q. v.], who expect El-Mahdee's coming forth from the سِرْدَاب that is in Rei, wherefore they bring a saddled and bridled horse every Friday, after the prayer [of the congregations at noon], saying, “O Imám: in the name of God:” three times. (TA.)