Ciphers (5)
I believe the answer is:
codes
'ciphers' is the definition.
('code' can be a synonym of 'cipher')
This is all the clue.
(Other definitions for codes that I've seen before include "Word systems devised to create secrecy" , "Ciphers" , "Lots of laws" , "Systems for transmitting secret messages" , "Sets of rules or cryptograms" .)