Compare <span class="searchmatch">Proto</span>-Indo-European *kakka-, which at least may have influenced/reinforced it. *<span class="searchmatch">kaka</span> excrement, faeces Aquitanian: *caca <span class="searchmatch">Basque</span>: <span class="searchmatch">kaka</span> R. L. Trask...
From <span class="searchmatch">Proto</span>-<span class="searchmatch">Basque</span> *<span class="searchmatch">kaka</span> (compare <span class="searchmatch">Basque</span> <span class="searchmatch">kaka</span>). *caca excrement, faeces shit <span class="searchmatch">Basque</span> Etymology...