Webster's Revised Unabridged Dictionary · 1913

Fissile

Fissile , adjective

[Latin fissilis, from fissus, past participle of findere to split. See Fissure.]

1.
Capable of being split, cleft, or divided in the direction of the grain, like wood, or along natural planes of cleavage, like crystals.
This crystal is a pellucid, fissile stone. — Sir I. Newton
2.
Fissionable.