The story
From Gaia + sausage. From being discovered by the Gaia Mission, a European Space Agency space telescope that maps the stars of the Milky Way, and forming a sausage-shaped plot in velocity-space.
Etymology from Wiktionary, CC BY-SA 4.0.
Gaia Sausage
Today it means: A stellar population within the Milky Way Galaxy that forms a sausage-shaped plot in velocity-space, which is thought to originate from a galaxy merger ten billion years ago, with the Gaia-Enceladus galaxy, composing mostly Milky Way halo stars. Full definition →