The concept of "secondary qualities" refers to the subjective, sensory experiences associated with objects, such as their color, texture, taste, and smell. The antonyms for secondary qualities would be "primary qualities," which are objective and measurable attributes of objects, such as their shape, size, weight, and motion. While primary qualities can be determined through empirical observation and scientific measurement, secondary qualities are more elusive and dependent upon individual perceptions and interpretations. By examining the relationship between primary and secondary qualities, philosophers and scientists can gain deeper insights into the nature of reality and the limits of human cognition.