What does "punctilious" mean?

Punctilious: Attentive to punctilio; very nice or exact in the forms of behavior, etiquette, or mutual intercourse; precise; exact in the smallest particulars. "A punctilious observance of divine laws." Rogers. "Very punctilious copies of any letters. The Nation. Punctilious in the simple and intelligible instances of common life. I. Taylor. -- Punc*til"ious*ly, adv. -- Punc*til"ious*ness, n.