ingenuousness comes from ingenuous + -ness, from Latin ingenuus ('native, freeborn, frank, noble'), from in- ('in') + gignere ('to beget'). 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 noun sense is "the quality of being frank, innocent, and free of guile", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as ingenuous, ingenue, and genuine. Its semantic neighborhood includes candor, frankness, artlessness, and innocence, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Latin ingenuus and Latin gignere.