Related to invasive: invasive lobular carcinoma, Invasive candidiasis. (ĭn-vā′sĭv) adj. 1. Of, engaging in, or given to armed aggression: an invasive military force. 2. a. Of or relating to a disease or condition that has a tendency to spread, especially into healthy tissue: an invasive carcinoma. b. Of or relating to a medical procedure in which a part of the body is entered, as by puncture or incision. 3. Tending to spread widely in a habitat or ecosystem. Used especially of nonnative species: an invasive grass. 4. Tending to intrude or encroach, as upon privacy.