/spi nel", spin"l/ , n.
1. any of a group of minerals composed principally of oxides of magnesium, aluminum, iron, manganese, chromium, etc., characterized by their hardness and octahedral crystals.
2. a mineral of this group, essentially magnesium aluminate, MgAl 2 O 4 , some varieties being used as gems.
Also, spinelle .
[ 1520-30; spinelle spinella, equiv. to spin ( a ) thorn ( spina ) + -ella -ELLE ]