Boaō (βοάω) means to cry out, to call loudly, or to shout. It conveys urgent, passionate, or desperate calling — the cry of one who needs to be heard across a distance or amid a crowd. The word is used for John the Baptist's voice in the wilderness, for those crying out to Jesus for healing, and for the prophetic proclamation of Isaiah.
Every cry of boaō in Scripture points to a fundamental human need before God. John the Baptist as "the voice of one crying in the wilderness" (Isaiah 40:3; Matthew 3:3) embodies this cry perfectly — urgent, persistent, calling for preparation. The blind men who cried out "Son of David, have mercy!" (Matthew 20:30) model the desperate, persistent prayer that God honors. Boaō is the sound of faith in action.