ˈȯrˌthrȯs noun
or or·thron -thrȯn
( plural orthroses or orthrons )
Usage: often capitalized
Etymology: orthros from Late Greek, from Greek, dawn, sunrise; orthron from Middle Greek or New Greek, alteration of Late Greek orthros; akin to Greek orthos straight, upright — more at orth-
: the morning office in the Eastern Orthodox Church somewhat corresponding to the Latin lauds