*(o)uxs- (“up”) + *-teros, albeit with the prefix-final -s- absent. *<span class="searchmatch">ouxteros</span> upper <span class="searchmatch">Proto</span>-Brythonic: *ʉθr Middle Welsh: uthyr, uthir, uthr (“terrifying, terrific”)...
it. <span class="searchmatch">Proto</span>-<span class="searchmatch">Celtic</span> terms prefixed with *(o)uxs- Reconstruction:<span class="searchmatch">Proto</span>-<span class="searchmatch">Celtic</span>/ouxsanatā Reconstruction:<span class="searchmatch">Proto</span>-<span class="searchmatch">Celtic</span>/<span class="searchmatch">ouxteros</span> *ouxselos *ouxsos *<span class="searchmatch">ouxteros</span> Old...