The name "Ame no Murakumo" is based on the legendary Kusanagi-no-Tsurugi sword of Japanese myth. It was originally called Ame-no-Murakumo-no-Tsurugi (天叢雲剣?) which roughly translates as "Sword of the Gathering Clouds of Heaven", but its name was later changed to the more popular Kusanagi-no-Tsurugi ("Grass Cutting Sword"). In legend, the sword is found by the storm god Susano'o in one of the tails of the Yamata no Orochi. It's also one of the three Imperial Regalia used in the ritual of imperial ascension.
See Special:Whatlinkshere/Etymology:Ame no Murakumo for a list of articles using this term.