What is the X in X-mas?
"to move quickly," 1530s, of uncertain origin, perhaps a variant of Middle English scut "rabbit, rabbit's tail," in reference to its movements (see scut (n.1)), but there are phonetic difficulties. Perhaps rather from a North Sea Germanic source akin to Middle Low German, Middle Dutch schudden "to shake" (see quash). Related: Scudded; scudding. As a noun from c.1600, from the verb. It also was the NATO reporting name for a type of Soviet missile introduced in the 1960s.