Intrusion
Part of speech: noun
Definition: The forcible inclusion or entry of an external group or individual; the act of intruding.
Example sentence: What happens with smaller businesses is that they give in to the misconception that their site is secure because the system administrator deployed standard security products - firewalls, intrusion detection systems, or stronger authentication devices such as time-based tokens or biometric smart cards. But those things can be exploited.
Invasion
Part of speech: noun
Definition: A military action consisting of armed forces of one geopolitical entity entering territory controlled by another such entity, generally with the objective of conquering territory or altering the established government.
Example sentence: For a war correspondent to miss an invasion is like refusing a date with Lana Turner.