Unfit means not suitable, not qualified, or not in good enough condition for a particular purpose or role. When something is unfit, it lacks the necessary qualities to do what's needed.

A bridge might be declared unfit for traffic if engineers find cracks that make it unsafe to drive across. Food that's spoiled or contaminated is unfit to eat. A person who hasn't exercised in years might feel unfit to run a marathon because their body isn't prepared for that challenge.

The word often appears in serious contexts. A judge might rule that someone is unfit to serve as a guardian if they can't properly care for a child. A doctor might tell a pilot they're temporarily unfit to fly due to an injury. Military recruits who can't meet physical standards might be found unfit for service.

When you call something unfit, you're making a judgment that it doesn't measure up to what's required. A rusty, wobbly ladder is unfit for climbing. A student who hasn't learned the material is unfit to take an advanced exam. The word suggests that meeting certain standards matters, and whatever is unfit simply doesn't meet them.