The term "in-grained" refers to a deeply rooted habit or belief. Its antonyms include words such as "flimsy," "superficial," and "shallow," which connote a lack of depth or durability. Other antonyms may include "flexible," "manageable," and "adaptable," which suggest the ability to change or adjust to different circumstances or situations. These antonyms emphasize a lack of rigidity or fixedness, indicating that the opposite of "in-grained" is a willingness to consider different perspectives, experiment with new ideas, and approach challenges with an open mind.