Final answer:
A passport is a legal document that allows crossing borders between countries.
Step-by-step explanation:
The word that best fits the definition of 'Documento legal que nos permite cruzar de un país a otro' is passport. A passport is an official document issued by a government that allows its holder to travel internationally. It serves as proof of identity and citizenship. Passports contain personal information and are necessary for crossing borders and entering another country.
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