Irimi nage (入り身投げ)
Irimi: enter.
Nage: projection.
Irimi is the root of aikido. The ideogram iri expresses the idea of crossing the door of the house, on one's own initiative or being invited. And the ideogram mi It evokes the child in its mother's womb, with a sense of fullness, fullness of flesh and life. So irimi would be placing one's own body within the body of one's partner.
More prosaically, irimi is penetrating the other's line of attack, their defense, thereby causing an imbalance.
Irimi nage is one of the most characteristic throws in aikido. It involves knocking uke off balance from his neck or nape, then throwing him to the ground with the inside of the arm.
We will have to leave his line of force, trying to enter towards his back to begin his imbalance.