The story
From mini- + Magellanic Clouds. From being a Magellanic Cloud that is smaller than the Small Magellanic Cloud.
Etymology from Wiktionary, CC BY-SA 4.0.
Mini Magellanic Cloud
Today it means: A galaxy, a dwarf galaxy that is a satellite galaxy of the Milky Way Galaxy, and a member of the Magellanic Clouds, in the Mily Way Subgroup of the Local Group of Galaxies; lying directly behind the Small Magellanic Cloud, as seen from Earth. Full definition →