From Old Irish súil (“eye, hope”), from Proto-Celtic *sūli- (“sun”) (compare Welsh haul (“sun”), from Proto-Celtic ablaut variant *sāwol-), from Proto-Indo-European *sóh₂wl̥ (“sun”). The change in meaning in Old Irish is apparently due to the mythological view of the sun as the "eye of the sky".
after "yn", tooill
|Note: Some of these forms may be hypothetical. Not every
possible mutated form of every word actually occurs.