Where does “intense” come from?

intense (Old French) comes from Latin intēnsus, from Latin intendō, from Latin īn-, from Latin în, from Latin en, from Proto-Italic en, from Proto-Indo-European h₁én — in.

Ancestry of “intense”, step by step

Step	Language	Word	Meaning
1	Latin	intēnsus	intent, eager
2	Latin	intendō	to stretch out; to strain
3	Latin	īn-	un-, non-, not
4	Latin	în	in, at, on, upon, from (space)
5	Latin	en	lookǃ beholdǃ; reallyǃ?; come onǃ
6	Proto-Italic	en	in
7	Proto-Indo-European	h₁én	in

Words derived from “intense”

Every word from Proto-Indo-European h₁én →Every word from Latin īn- →Every word from Proto-Italic en →