Other forms: invaded, invading, invades
To invade is to enter a country by force with an army. Invade the mainland, an invading force, the country was invaded.
It is also used of anything unwelcome arriving in quantity: tourists invaded the town, invaded by mice. Invade somebody's privacy is a fixed phrase and a legal concept. In medicine, invasive describes both a cancer spreading and a procedure that enters the body — the two senses sit awkwardly together. Note invader, invasion; and non-invasive, which is what everybody hopes their test will be.
1verbinvadeTo enter a country by force with an army.
“Germany invaded Poland in September 1939.”
2verbarriveTo arrive somewhere unwelcome in quantity.
“Every summer, tourists invade the little fishing village.”
invade is a forceful entering.
Latin invadere is in-, into, plus vadere, to go. The same vadere gives evade and pervade, so invading, evading and pervading are three directions of one verb.
Proto-Indo-European
*weh₂dʰ-
Latin
invādō — enter, invade
English, today
invade
From Latin invādō (“enter, invade”).
Etymology from Wiktionary, CC BY-SA