1. to lack the ability, means, or opportunity to accomplish or reach a goal
Despite his efforts, he was unable to achieve his dream of becoming a professional athlete.
Apesar de seus esforços, ele não conseguiu alcançar seu sonho de se tornar um atleta profissional.
2. to fail in accomplishing something due to lack of capability or resources
The company was unable to achieve its sales targets this quarter.
A empresa foi incapaz de atingir suas metas de vendas neste trimestre.