Impeccable means faultless in every detail. Impeccable manners, impeccable timing, impeccably dressed.
It is used of things done to a standard nothing can be picked at: impeccable credentials, impeccable English, impeccable taste. It is stronger than excellent because it claims the absence of any fault rather than the presence of quality. The word literally means incapable of sin, from Latin peccare, and its first use in English was theological. Note impeccably; and peccadillo, a small sin, from the same verb.
1adjectiveimpeccableFaultless in every detail.
“The hotel's service was impeccable from the moment we arrived.”
synonyms: flawless, faultless
impeccable is a quality of faultlessness.
You already know sin. The Latin behind this word is peccare, to sin, and impeccable is what has none in it at all: not one wrong note, not one loose thread, nothing anybody can point at.
hooks ontosin
Latin impeccabilis is in-, not, plus peccare, to sin. Peccadillo and the confession mea culpa's peccavi come from the same sinning, so impeccable means literally sinless.
Proto-Indo-European
*ped-
Latin
impeccabilis — not liable to sin
Middle French
impeccable
English, today
impeccable
Built from
From Middle French impeccable, from Latin impeccabilis (“not liable to sin”), from im- (“not”) + pecco (“to err, to sin”).
Etymology from Wiktionary, CC BY-SA