The “bow” in “rainbow” is just one of many forms:
Rainbows take many forms. Multiple bows, bows that cross, red bows, twinned bows, coloured fringes, dark bands, spokes and more.
For instance:
Alexander’s dark band
Cloud bows
Glassbows
High order bows
High & low bows
Moonbows
Primary bows
Red bows
Reflection bows
Seawater bows
Secondary bows
Supernumeraries
Twinned bows
See also: this past weekend