From {{etyl|dum|nl}} {{term|ruuch|lang=dum}}, {{term|ru|lang=dum}}, {{term|rou|lang=dum}}, from {{etyl|odt|nl}} *{{termrecons|ruh|rūh|lang=odt}}, *{{termrecons|ru|rū|lang=odt}}, from {{etyl|gem-pro|nl}} {{recons|rūhaz|lang=gem-pro}}. The original stem ended in -h-, which disappeared between vowels, giving *{{termrecons|ru-|rū-|lang=odt}} in the inflected forms in Old Dutch. This then gave rise to an alternative uninflected form *{{termrecons|ru|rū|lang=odt}}, which developed into Middle Dutch {{term|ru|lang=dum}}, {{term|rou|lang=dum}}, modern Dutch {{term|ruw|lang=nl}}, {{term|rouw|lang=nl}}. The original uninflected form was back-formed to {{term|ruig|lang=nl}} based on other words with -ch in the uninflected form and -g- in inflected forms, similar to what happened to {{term|hoog|lang=nl}}.
