What does "rigid" mean in simple words?

Rigid means stiff and not bending, like a board that does not flex when you push it, and also means not willing to change or adapt, like person who insists on doing things only one way and gets upset when plans change. In simple words, rigid means hard to bend, hard to move, and hard to change. For objects, rigid means solid and firm that keeps its shape, opposite of flexible or soft. For rules, rigid means strict rules that cannot be changed or broken. For people, rigid means stubborn and set in their ways, not open to new ideas. So in simple words, rigid means stiff, inflexible, strict, and unyielding, describing something or someone that does not bend, does not flex, and does not adapt easily, whether physical object that stays stiff or person who sticks to routines and resists change.