synflood noun 1verb 1forms 3 noun1 •(Internet) A denial-of-service attack in which the attacker sends a succession of SYN (synchronization) requests to the target system in an attempt to consume its resources and make the system unresponsive to legitimate traffic. verb1 •(Internet) To carry out an attack of this kind. formssynflooded · synflooding · synfloods