si·ma 
(sīmə)
(sīmə)n.
The lower layer of the earth's outer crust that underlies the sial and is rich in silica, iron, and magnesium.
[SI(LICA) + MA(GNESIUM).]
- preceramic
- precess
- precession
- precessional
- precession of the equinoxes
- pre-Christian
- precinct
- preciosity
- precious
- preciously
- precious metal
- preciousness
- precious stone
- precipice
- precipitable
- precipitance
- precipitancy
- precipitant
- precipitantly
- precipitate
- precipitately
- precipitateness
- precipitation
- precipitative
- precipitator