1. A grammatical form that is clearly determined or specified; in linguistics, particularly referring to nouns or articles that have a definite, specific reference
In Portuguese, 'o' and 'a' are definite articles that mark the definite form of nouns.
Em português, 'o' e 'a' são artigos definidos que marcam a forma definida dos nomes.
2. A shape, structure, or configuration that is clearly outlined or precisely determined
The architect presented a definite form for the building design.
O arquiteto apresentou uma forma definida para o design do edifício.