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Webster 1913 Edition
Khamsin
{ 
, Kam-sin′
,Kham-sin′
}Noun.
 [Ar. 
khamsīn
, fr. khamsūn
, oblique case khamsīn
, fifty; – so called because it blows for about fifty days, from April till June.] A hot southwesterly wind in Egypt, coming from the Sahara. 
[Written also 
 Khamseen
.]