Punctilious

General Very attentive to detail, scrupulous and exact.

Origin
This word derives from Late Latin "punctillum", which means 'a little point', and this from Latin "punctum", meaning 'prick'.

Vocabulary
"Punctilious" is a by-word for "meticulous" or "painstaking". While these two by-words stress extreme care, "punctilious" specifically refers to minute details of conduct:
"The more unpopular an opinion is, the more necessary is it that the holder should be somewhat punctilious in his observance of conventionalities generally" (Samuel Butler).