Characterized by careful, regular, and devoted attention; marked by constant or continuous application.
From Latin assiduus (sitting constantly, diligent) from assidere (to sit at) + -al suffix. The sense evolved from 'sitting constantly at a task' to 'doing something diligently.'
The root of 'assiduus' is literally 'sitting down'—Romans believed that real work and learning required sitting down and staying put, which is why sitting became the symbol for serious dedication.
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