audacious

From Latin audacia ("boldness") plus the suffix -ious, with audacia itself coming from audax ("bold"), rooted in the verb audeo ("to be bold, to dare").

The facts don't show a shift in meaning over time — the word has stayed tied to its root sense of boldness from audeo through audax and audacia into English.

It shares its root audeo with audax, the Latin word for "bold" that gave audacious its backbone.