Epiboaō combines epi (upon/toward) + boaō (to cry out). It means to cry out loudly toward someone — an urgent, public, passionate vocal appeal. It appears only once in the NT, in Acts 25:24, where the Jewish leaders cry out against Paul before Festus.
Epiboaō captures the intensity of urgent appeal. The Jewish leaders shouting against Paul ironically mirror the crowds who cried out against Jesus. But the word's root (boaō) also captures the prophetic cry: Isaiah crying in the wilderness (John 1:23), the crowds crying "Hosanna," the blind men crying "Son of David, have mercy on us." The theology of boaō is that God hears the cry — especially of the helpless. "This poor man cried out [ekekragen] and the LORD heard him" (Psalm 34:6). Crying out to God is not weakness; it is faith.