Assiduity

As`si*du"i*ty (?), n.; pl. Assiduities (?). [L. assiduitas: cf. F. assiduite. See Assiduous.] 1. Constant or close application or attention, particularly to some business or enterprise; diligence.

I have, with much pains and assiduity, qualified myself for a nomenclator.
Addison.

2. Studied and persevering attention to a person; - - usually in the plural.