'retransmit' originates from Latin and English formation: the prefix 're-' (from Latin 're-') meaning 'again' combined with 'transmit', which comes from Latin 'transmittere' where 'trans-' meant 'across' and 'mittere' meant 'to send'.

'transmit' came into English via Old French 'transmettre' from Latin 'transmittere'; 'retransmit' is a modern English formation (re- + transmit) meaning 'send again', and 'retransmitted' is its past/past-participle form.

Initially, the root 'transmit' meant 'to send across'; with the prefix 're-' the combined form came to mean 'to send again' (the sense has shifted from simply 'send across' to 'send again' when 're-' is added).