- A nebula, such as the Ring Nebula, consisting of a hot, blue-white, central star surrounded by an envelope of expanding gas.行星状星云：由一颗炽热的、蓝白色的中心恒星和包围它的一层向外膨胀的气体组成的星云，如环状星云
- microampere
- microanalysis
- microanalytical
- microanatomy
- microbalance
- microbar
- microbarograph
- microbe
- microbes
- microbiology
- microbrew
- microbrewery
- microbubble
- microburst
- microbus
- microcap
- microcapsule
- microcephalies
- microcephaly
- microchemistry
- microchip
- microcircuit
- microcirculation
- microclimate
- microcline