Where does “tuig” come from?

tuig (Irish) comes from Middle Irish tuicid, from Old Irish ·tucci, from Proto-Celtic *unketi, from Proto-Indo-European *h₁unékti.

tuig (Irish): understand

Definitions

Step	Language	Word	Meaning
1	Middle Irish	tuicid	—
2	Old Irish	·tucci	—
3	Proto-Celtic	*unketi	—
4	Proto-Indo-European	*h₁unékti	—

tuig — Etymology, Origin & Word History | Etymology Explorer