Etymology: Partly < Spanish pecadillo (first attested 1545–65, although probably earlier: compare peccadilian n.) < pecado sin ( < classical Latin peccātum error, moral lapse, in post-classical Latin also sin (Vetus Latina) < peccāre (see peccant adj. and n.) + -ātum -ate suffix1) + -illo , diminutive suffix (see -illus suffix), and partly < Italian peccadiglio (1534) < Spanish pecadillo
A minor fault or sin; a trivial offence. (OED)
"“It isn’t a strong case for intentional misconduct. It seems it’s peccadilloes,” says Pierre Pica, a linguist at the French National Center for Scientific Research in Paris, who has criticized the investigation."
- Eugenie Samuel Reich, "Misconduct ruling is silent on intent", 13 September 2012 Nature