The term 'transmit again' can be expressed in two ways: RESEND (6 letters) and RETRANSMIT (10 letters). RESEND means to send something again, while RETRANSMIT means to send something back or to send it a second time. Both terms refer to the act of sending something that has already been sent. This could be done for a variety of reasons, such as if the original transmission was not received or if the sender wants to make sure the recipient has received the message.