Definition of "Rigid" :

adjective: incapable of or resistant to bending

"A rigid strip of metal."

adjective: designating an airship or dirigible having a form maintained by a stiff unyielding frame or structure

adjective: incapable of adapting or changing to meet circumstances

"A rigid disciplinarian."

adjective: fixed and unmoving

"A face rigid with pain."

adjective: incapable of compromise or flexibility