Where does “intruding” come from?

Intruding comes from Latin intrudere, composed of the prefix in- and trudere, ultimately deriving through Proto-Indo-European ne and h₁én.

intruding (English): present participle of intrude; intrusion

Definitions

Step	Language	Word	Meaning
1	English	intrude	To thrust oneself in; to come or enter without...
2	Latin	intrudere	—
3	Latin	in-	un-, non-, not; in, within, inside
4	Latin	in	in, at, on, upon, from; within, while in; into,...
5	Old Latin	en	in
6	Proto-Italic	en	in
7	Proto-Indo-European	h₁én	in