to cry out loudly: to shout or clamor, often with a raucous, insistent voice
This word names a loud vocal outburst, not ordinary speaking or a calm call. It is the roar of a crowd worked up to a pitch, and it is also the single voice raised at full volume in urgency or acclamation. In every case the point is the sheer force of the sound.
John's account of Jesus before Pilate returns to this word again and again as the crowd shouts the governor down: "Not this man, but Barabbas," then "Crucify him," then "Away with him." The same verb carries the crowd's "Hosanna" at the entry into Jerusalem and the mob that screams for Paul's death. It can also describe one loud cry rather than a crowd: Jesus shouting "Lazarus, come out" at the tomb, and unclean spirits crying out that they know who Jesus is.
It sits close to the more common verb κράζω, a piercing scream or croak, and to its own related noun κραυγή, "outcry" or "clamor." Matthew leans on that raucous coloring by negation: quoting Isaiah, he says the chosen Servant "will not cry out" or raise his voice in the streets, a quiet dignity set deliberately against the kind of public shouting this word usually names.