a very minor or slight sin or offense; a trifling fault.
Origin: 1585–95; < Spanish pecadillo, diminutive of pecado sin < Latin peccātum transgression, noun use of neuter of past participle of peccāre to err, offend
"slight sin," 1591, from Sp. pecadillo, dim. of pecado "a sin," from L. peccatum "a sin, fault, error," from neut. pp. of peccare "to make a mistake, sin," of unknown origin.