- MiraA binary star in the constellation Cetus, Omicron (ο) Ceti. The system contains a variable red giant and a white dwarf. Its brightness varies from a magnitude 2 at its brightest to a magnitude 10 at its dimmest.
- mirorderA taxonomic ranking just below grandorder and above order.
- mirusvirusA virus of the phylum Mirusviricota, a widespread group of plankton-infecting viruses which forms a "missing link" between giant viruses and herpesviruses.