"Most stiffnecked" refers to someone who is stubborn and inflexible in their thinking or behavior. Some antonyms for this phrase could include "open-minded," "flexible," "adaptable," "receptive," and "malleable."
An open-minded person is someone who is willing to consider different perspectives and ideas, making them the opposite of someone who is most stiffnecked. Flexibility and adaptability imply a willingness to change and adjust in response to new situations, while being receptive suggests an openness to new experiences and learning.
Malleability is another antonym for "most stiffnecked," implying a pliability and willingness to be shaped or molded by new experiences or ideas. These antonyms highlight the importance of being open to new experiences and ideas to avoid getting stuck in rigid thinking patterns.