Heedless comes from heed plus the suffix -less; heed comes from Old English hēdan ('to take care, attend to'), from Proto-Germanic *hōdijaną. The suffix is part of the word's derivational shape, marking the final grammatical or semantic role while the base supplies the central meaning. As an adjective, it carries the sense "showing a reckless lack of care or attention", with the older formation still helping explain the modern use. Relevant historical forms include Old English hēdan. Derivative forms include heedlessly, heedlessness; related words include heed, heedful.