General opposites:
* Humble: This is a common opposite, suggesting modesty and lack of self-importance.
* Simple: This conveys a lack of extravagance or complexity.
* Modest: Similar to humble, but with a focus on avoiding ostentation.
* Unassuming: This emphasizes a lack of pretension or self-promotion.
Specific opposites depending on context:
* Realistic: If grandiose is used to describe an unrealistic or exaggerated idea, realistic would be the opposite.
* Practical: If grandiose is used to describe an impractical or overly ambitious plan, practical would be the opposite.
* Down-to-earth: If grandiose refers to someone who is detached from reality, down-to-earth would be the opposite.
* Ordinary: If grandiose is used to describe something exceptional or extraordinary, ordinary would be the opposite.
Ultimately, the best opposite will depend on the specific situation and the nuance you're trying to communicate.