سُدٌّ

Also (assumed tropical:) A swarm of locusts obstructing the horizon: (M:) or so سُدٌّ مِنْ جَرَادٍ: (TA:) and جَرَادٌ سُدٌّ (tropical:) locusts (S, M, A, K) that have obstructed, (S, K,) or obstructing, (M, A,) the horizon, (S, M, A, K,) by their multitude: (S, A, K:) in which case, سُدٌّ is either a substitute for جَرَادٌ and therefore a substantive, or it is plural of سَدُودٌ signifying that which obstructs the horizon and therefore an epithet. (M.)

And (tropical:) A black cloud, (AZ, S, K, TA,) that has risen in any tract of the sky: (TA:) or a collection of clouds rising, obstructing the horizon: (M:) plural سُدُودٌ: (S, M, K:) [or] سَدٌّ and صَدٌّ, but the former is the more approved, signify (assumed tropical:) a cloud, or collection of clouds, rising high, and appearing like a mountain. (M and L in article صد.)

And A valley: (K:) so called because it becomes closed, or stopped up. (TA.)

And A valley containing stones and masses of rock, in which water remains for some time, or a long time: plural سِدَدَةٌ: (S, L, K:) or you say, أَرْضٌ بِهَا سِدَدَةٌ [a land in which are valleys containing stones and masses of rock, &c.]; and the singular is سُدَّةٌ. (L.)

And (assumed tropical:) The departure [or loss] of sight: (IAar, M:) from the same word in the first of the senses explained in the next preceding paragraph. (M.)