water-gall
/ˈwɔːtəˌɡɔːl/(also water-geal, water-gaw, watter-gaw)
noun
A secondary or imperfectly-formed rainbow; (more widely) any of various phenomena in the clouds and sky that are believed to be portents of approaching rain. Also in extended use. regional in later use (now chiefly Scottish ).
Origin
Late 16th century; earliest use found in Thomas Twyne (1543–1613), physician. From water + gall.