The word "stick-to-itiveness" is a term used to describe the quality of being persistent and determined, especially in the face of obstacles or challenges. Antonyms for this word might include terms like "indecisiveness," "unreliability," or "fickleness," which suggest a lack of dedication or the tendency to give up easily. Other antonyms might include "timidity," "cowardice," or "lack of conviction," which reflect a lack of confidence or willingness to take risks. Ultimately, the antonyms for "stick-to-itiveness" all suggest a lack of commitment or an unwillingness to persevere in the face of difficulties.