Meticulous
From 'Vocabulary' part of The ABC Of Plain Words by Sir E Gowers (1951)

Meticulous is derived from a Latin word meaning timid, and like its plebeian cousin pernickety, still retains a flavour of fussiness over trifles. It should only be used where the writer wants to emphasise that carefulness is overdone; it should not be treated as a synonym for scrupulous or any other commendatory word.