eDIL separates two Irish headwords written cais. The first, also recorded as caise, is explicitly explained both as love and as hate; its cited passages and glossary equations range from searc and grádh "love" to miscais and mioscais "hatred", with context deciding individual readings. One Éigse line is tentatively translated so that the same visible form occurs on both sides: "my love ... is met by hatred(?)". The question mark matters. The second eDIL headword cais means "eye" and is excluded from this semantic lineage. These records establish a remarkable lexicographic opposition, not one timeless essence, a chronology from love to hate, or proof that every occurrence belongs to one historically indivisible sense. John T. Koch compares the noun with Proto-Celtic *katsi- < *kad-t/si- and a wider *kad- family, but that ancestry and its proposed Germanic comparison remain open. eDIL itself generally supplies etymologies only selectively. No manuscript pixels were directly inspected, no earliest-use or historical-frequency claim is made, and no exact pronunciation is invented.