The supplying of something from outside rather than letting a thing make its own. Also the introducing of what does not belong — the same word for a design pattern and for an attack.
Latin inicere (to throw in, cast into), from in- (into) + iacere (to throw); the introducing of something from outside — a design pattern's virtue and an attack's method share this one root.
One word carrying two opposite reputations — the deliberate supplying of what a part needs, and the unwanted introducing of what does not belong, told apart only by consent.