Translation:The child knows the bilingual password.
I am puzzled by the meanings of σύνθημα; I learned as 'slogan', somewhere, and the translations in some of the exercises here as 'cue' don't seem to make much sense to me, so perhaps there are some issues of meaning to be sorted out here
In Polish it's similarly bifold: hasło - meaning password as well as slogan.
Ah! Thanks for your input, alex.stereo! It makes it clear: Greek speakers make sense with a δίγλωσσο σύνθημα when σύνθημα can be translated as 'cue' or 'slogan', while when translated as 'password' 'bilingual' doens't make sense...
:-D "password" as in Marx bros' movie? then such as "swordfish" — hence 'password' should be a "pass phrase", in order to let room for the 'bilingual' aspect!!! (tricky ain't it!? )