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
High order bows
High & low bows
Primary bows
Red bows
Reflection bows
Seawater bows
Secondary bows
Twinned bows

See also: this past weekend