indignation comes from Latin indignatio ('displeasure, anger'), from indignari ('to regard as unworthy, be angry'), from indignus ('unworthy'), from in- ('not') + dignus ('worthy'). Morphologically, the prefixed shape matters: the initial element belongs to the recorded formation and helps explain the modern form's surface analysis. In present English, the noun sense is "anger aroused by something perceived as unjust or unworthy", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as indignant, indignity, dignity, and disdain. Its semantic neighborhood includes anger, resentment, outrage, and wrath, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Latin indignari, Latin dignus, and Proto-Indo-European *deḱ-.