Unable to be broken or destroyed; very strong and durable.
From 'un-' (not) + 'break' (from Old English 'brecan') + '-able' (capable of being); the suffix '-able' means 'capable of being broken,' so 'unbreakable' reverses that.
Materials scientists obsess over 'unbreakable' because it's technically a promise impossible to keep—everything breaks under enough stress—but marketing loves calling things unbreakable because it appeals to our desire for permanence.
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