Where does “thairis-sean” come from?

thairis-sean (Irish) comes from Irish thairis, from Irish thar, from Old Irish tar, from Old Irish a, from Proto-Celtic *ā, from Proto-Indo-European ō — oh, ah.

thairis-sean (Irish): third-person singular masculine emphatic of thar

Definitions

third-person singular masculine emphatic of thar

Ancestry of “thairis-sean”, step by step

Step	Language	Word	Meaning
1	Irish	thairis	third-person singular masculine of thar
2	Irish	thar	over; by, past; through; beyond
3	Old Irish	tar	over, across
4	Old Irish	a	nominative/accusative singular neuter of in; that...
5	Proto-Celtic	*ā	O (vocative particle)
6	Proto-Indo-European	ō	oh, ah

Every word from Proto-Indo-European ō →Every word from Proto-Celtic *ā →Every word from Old Irish a →