The word 介入 is formed by combining two pictographic characters that create a vivid conceptual image: 介, which originally depicted a person clad in armor (evoking the idea of a boundary, shell, or intermediary), is placed before 入, a clear pictogram of something entering. Together, they visually construct the notion of "stepping into the middle", forming the meaning of to intervene or become involved, as if one enters (入) the space between or the armored boundary (介) separating two parties.