1. to vary or change in an unpredictable, irregular, and unstable manner; to rise and fall without pattern or consistency
The stock market prices fluctuate erratically during times of economic uncertainty.
Os preços do mercado de ações flutuam erraticamente durante períodos de incerteza econômica.
2. to move back and forth or up and down in an inconsistent or random way
Her mood fluctuates erratically, making it difficult to predict her reactions.
Seu humor flutua erraticamente, tornando difícil prever suas reações.