For EASA licences the definition is in FCL.010 of
Part-FCL:
"Cross-country" means a flight between a point of departure and a point of arrival following a pre-planned route, using standard navigation procedures.
The aerodromes of departure and arrival may be the same unless the context requires otherwise.
... the minimum requirements before being allowed to start...
Distinction should be made between course commencement and application requirements.
If you intend to additionally obtain standard US or Canadian flight crew licences then be aware that they are based on more rigorous definitions.