Definition

Not steady or firm; likely to change or fall apart easily.

Example

The unstable structure of the building made it dangerous to enter.

Conversation

I heard the weather might be unstable this weekend.

Yeah, I saw that too; it might rain or even snow!

That's so unpredictable — I hope it doesn't ruin our plans.

Same here! We should have a backup option just in case.

Synonyms & Antonyms

Root Explanation

Unstable → It is formed from "un-" (meaning not) and "stabilis" (from Latin, meaning stable or fixed). The word "unstable" means not stable or lacking firmness and steadiness.

Memory Tip

Think of 'not' ('un-') being added to 'stable' — this helps you remember that 'unstable' means something that is not steady or secure.

Visually Confused Words