The word "unflexible" implies the lack of ability to change or bend. Antonyms for this word can include "flexible," "adaptable," "pliable," "versatile," "malleable," and "ductile." Being flexible means having the ability to adjust to new circumstances, ideas, or situations. Adaptable refers to the ability to modify oneself or one's behaviors to suit changing circumstances or requirements. Pliable means capable of being easily shaped or molded. Versatile means capable of adapting to many different situations or activities. Malleable implies the ability to be easily influenced or shaped by external factors, while ductile means capable of being bent or stretched without breaking.