unstable

Definition

Not stable.

Etymology

From Middle English unstable; equivalent to un- (not) + stable.

Example Sentences

• "unstable foundation"
• "The structure is too unstable to stand safely."
• "The hillside at this point is composed of shaly rock overlaid with a peaty loam which carries a growth of heather, and its unstable condition has resulted in two landslides in the course of the railway's history."