The Oxford introduction to <span class="searchmatch">Proto</span>-<span class="searchmatch">Indo</span>-<span class="searchmatch">European</span> and the <span class="searchmatch">Proto</span>-<span class="searchmatch">Indo</span>-<span class="searchmatch">European</span> world, Oxford University Press, page 99: “*póntōh₂<span class="searchmatch">s</span>” ^ Pokorny, Julius (1959)...
Likely derived from a lost substantive *fanþ-, from <span class="searchmatch">Proto</span>-<span class="searchmatch">Indo</span>-<span class="searchmatch">European</span> *<span class="searchmatch">pónth</span>₁<span class="searchmatch">s</span>, *pónteh₁<span class="searchmatch">s</span>. For the noun, compare Ancient Greek πόντος (póntos, “sea”)...