rigid

The word rigid describes something that is unable to bend or be easily changed; it's stiff and inflexible. This applies both physically and figuratively. A rigid pipe won't flex, a rigid schedule leaves no room for spontaneity, and a rigid belief system resists new ideas.

Historically, rigid comes from the Latin word rigidus, meaning "stiff" or "fixed." This sense of not bending is central to its meaning. You might describe a wooden board as rigid, contrasting it with something pliable like fabric.

But rigidity isn't always negative. In engineering, a rigid structure can be desirable when it needs to hold its shape firmly under force. However, when applied to people or ideas, rigid often carries a connotation of inflexibility and unwillingness to compromise. A rigid personality might struggle to adapt to new situations or understand different perspectives.

You can also use rigid to describe something that is strictly enforced or adhered to: "The company has a rigid policy on employee dress code." Or, you could say someone showed "rigid control" over a situation, meaning they were very strict and uncompromising in their approach.

So, whether describing physical materials, personality traits, or rules and regulations, rigid signifies an inability or unwillingness to bend, change, or yield.