What does increasing send delay actually mean,

What does this mean and can I prevent it or help it in someway?

“Increasing send delay for ...* from 0 to 5 due to 11 out of 14 dropped probes since last increase.”

Increasing send delay means that Nmap sends packets slowly to the server you are trying to probe on. Instead of sending it in 1 sec, it has increased that to 5 secs as all the packets that Nmap sent didn’t return anything. You cannot prevent it as sometimes the server you are trying to probe has a certain mechanism that stops the huge inflow of packets. That’s why Nmap by itself reduces the number of packets it sends to that server

Thank you for the reply.