What term indicates the act of making something better or more effective?

The term that indicates the act of making something better or more effective is "refine." This word conveys the process of improvement, where something is enhanced through careful adjustments or modifications. Refinement often involves removing impurities or adding nuance, leading to a more polished and effective outcome.

In contrast, while "emphasize" refers to giving special significance or importance to something, it does not inherently imply improvement. "Develop" suggests growth or evolution, but it can pertain to creating something new rather than improving an existing entity. "Support" typically means to hold up or assist, which does not directly involve the concept of enhancement or betterment. Thus, "refine" is the most appropriate term for the act of improving effectiveness.