Probably a modern elaboration of Andrea, from Greek roots meaning manly or brave.
Andreonna is probably a modern elaboration of Andrea, ultimately tied to Greek roots meaning manly or brave. Like many feminine forms built from older masculine names, it takes a durable classical stem and gives it a more ornate, contemporary shape.
The result is a name that sounds established even if the spelling is relatively new. Its ending gives it a ceremonial, almost embellished quality, which helps explain why names like Andreonna feel larger than their root forms. There is a modern taste for names that extend familiar classics with extra syllables, making them feel softer, more elaborate, or more individual.
Andreonna fits that pattern well: it suggests strength through inheritance, but presents it with a more decorative and expressive surface. That mix of firmness and flourish gives the name its character.