ideologic comes from ideology + -ic, from French ideologie, from Ancient Greek idea ('form, idea') + -logia ('study of'), from logos ('word, reason'). Morphologically, the ending is part of the etymology: the suffix is attached to the older base named in the history, producing a later English derivative. In present English, the adjective sense is "of or relating to ideology or a system of ideas", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as ideology, ideologue, and idea, and in derivatives such as ideologically. Its semantic neighborhood includes ideological, doctrinal, and theoretical, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Ancient Greek idea and Ancient Greek logos.