punc ‧ til ‧ i ‧ ous /pʌŋkˈtɪliəs/ BrE AmE adjective formal
[ Date: 1600-1700 ; Origin: punctilio 'detail of good behavior' (16-21 centuries) , from Italian puntiglio , from Spanish puntillo , from Latin punctum ; ⇨ ↑ point 1 ]
very careful to behave correctly and follow rules
punctilious about
Joe was always punctilious about repaying loans.
—punctiliously adverb
—punctiliousness noun [uncountable]