General synonyms:
* Stress
* Highlight
* Focus
* Importance
* Accent
* Weight
* Significance
* Prominence
* Emphasis
* Stress
* Pointing
* Call attention to
More specific synonyms:
* Amplification: (when you're making something larger or stronger)
* Exaggeration: (when you're making something seem bigger or more important than it is)
* Intensification: (when you're making something stronger or more intense)
* Reinforcement: (when you're making something stronger or more secure)
* Reiteration: (when you're repeating something to make it clear)
* Clarification: (when you're making something easier to understand)
The best synonym will depend on the specific context of your sentence.