intromission

noun

1. (countable, uncountable)The state of being allowed to enter; admittance
2. (countable, uncountable)The act of allowing to enter; admission
3. (countable, uncountable)Putting one thing into another; introduction (into); insertion

   “"Your father has told me all about it. Did you ever hear of anything so ridiculous?" "All about what?—all about what?" said Delia, whose attempt to represent happy ignorance seemed likely to be spoiled by an intromission of ferocity. She might succeed in appearing ignorant, but she could scarcely succeed in appearing happy.”

4. (countable, uncountable)Copulation: usually the first moment of initial entry of a penis into a vagina, mouth or anus.
5. (Scotland, countable, uncountable)An intermeddling with the affairs of another, either on legal grounds or without authority.