(1) Entrance by force or without permission or welcome
(2) Entry to another's property without right or permission
(3) Any entry into an area not previously occupied
"An invasion of tourists"
"An invasion of locusts"
(4) Rock produced by an intrusive process
(5) The forcing of molten rock into fissures or between strata of an earlier rock formation
- The forcible inclusion or entry of an external group or individual; the act of intruding.
- He viewed sales calls as an unwelcome intrusion.