fundamentar
substantiate
fundament
foundation, basis
+
-ar
verb suffix
Fundamentar means to substantiate and can be thought of as fundament0 (foundation, basis0) + -ar1 (verb suffix1), literally meaning 'to provide a foundation for'.
verb
- substantiateTo provide a basis or foundation for; to justify or support with reasonsNecesitas fundamentar tu argumento con evidencia. // You need to substantiate your argument with evidence.