per·ma·frost 
(pûrmə-frôst′, -frŏst′)
(pûrmə-frôst′, -frŏst′)n.
Permanently frozen subsoil, occurring throughout the Polar Regions and locally in perennially frigid areas.
[PERMA(NENT) + FROST.]
- microsecond
- microseism
- microseismic
- microsensor
- microsleep
- microsomal
- microsome
- microsomic
- microsporangiate
- microsporangium
- microspore
- microsporic
- microsporocyte
- microsporogenesis
- microsporophyll
- microsporous
- microstate
- microstructure
- microsurgery
- microsurgical
- microteaching
- microtome
- microtomic
- microtomy
- microtonal