Where does “locutio” come from?

locutio (Latin) comes from Latin loquor, from Proto-Italic tlokʷōr, from Proto-Indo-European telkʷ- — to talk.

Ancestry of “locutio”, step by step

Step	Language	Word	Meaning
1	Latin	loquor	I say, speak, tell, talk; I declare, utter
2	Proto-Italic	tlokʷōr	—
3	Proto-Indo-European	telkʷ-	to talk

locutio — Etymology, Origin & Word History | Etymology Explorer