sedulous

Etymology

Formed from Latin sēdulus (“diligent, industrious, sedulous; solicitous; unremitting; zealous”) and English -ous. Sēdulus probably derives from sēdulō (“diligently; carefully; purposely; zealously”), possibly from sē- (prefix meaning ‘without’) plus dolō (ablative singular of dolus (“deceit, deception; evil intent, malice”)), ultimately from Proto-Indo-European *del- (“to count, reckon”), plus -us (suffix forming adjectives).