1. Constant in application or attention; devoted; attentive; unremitting. She grows more assiduous in her attendance. Addison. 2. Performed with constant diligence or attention; unremitting; persistent; as, assiduous labor. To weary him with my assiduous cries. Milton. Syn. -- Diligent; attentive; sedulous; unwearied; unintermitted; perseverin...