Where does “súilaithne” come from?

súilaithne (Irish) comes from Irish súil, from Old Irish súil, from Primitive Irish sūli, from Proto-Celtic sūle, from Proto-Indo-European sóh₂wl̥ — sun.

súilaithne (Irish): Knowing by sight; recognising (a person) from their appearance

Definitions

Knowing by sight; recognising (a person) from their appearance

Ancestry of “súilaithne”, step by step

súilaithne traces back through two separate lines of ancestry.

via Irish súil

Step	Language	Word	Meaning
1	Irish	súil	eye
2	Old Irish	súil	eye; hope, expectation
3	Primitive Irish	sūli	—
4	Proto-Celtic	sūle	suns
5	Proto-Indo-European	sóh₂wl̥	sun

via Irish aithne

Step	Language	Word	Meaning
1	Irish	aithne	acquaintance, acquaintanceship; recognition; act...
2	Old Irish	aithne	verbal noun of ad·noí; an act of entrusting,...

Every word from Proto-Indo-European sóh₂wl̥ →Every word from Proto-Celtic sūle →Every word from Primitive Irish sūli →