idiotic comes from Late Latin idioticus, from Ancient Greek idiotikos ('of a private person, unskilled'), from idiotes ('layman, ignorant person'), from idios ('one's own'). The path is chiefly one of transmission: the word passes through the named languages and forms, with each stage preserving part of the modern shape. In present English, the adjective sense is "extremely foolish or stupid", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as idiot and idiocy, and in derivatives such as idiotically. Its semantic neighborhood includes foolish, stupid, absurd, and senseless, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Ancient Greek idiotes and Ancient Greek idios.