dold

n. pl. [ Cf. Gael. doltrum grief, vexation? ] A part of the ocean near the equator, abounding in calms, squalls, and light, baffling winds, which sometimes prevent all progress for weeks; -- so called by sailors. [ 1913 Webster ]

To be in the doldrums, to be in a state of listlessness ennui, or tedium. [ 1913 Webster ]