1. To speak aloud with studied rhetorical force and expression on a specific theme, as an exercise in public oratory: The preacher stood on the street corner, declaiming his beliefs about the evils of excessive drinking of liquor and smoking.
2. To speak in a passionate manner, appealing to emotions rather than to reason: The students stood in front of the university committee to declaim their membership in the "Flat Earth Society".

The senator declaimed against passing a bill that would raise taxes.

The priest was declaiming the funeral oration in loud and emotional feelings.