Perfect, faultless, flawless; free from faults or imperfections. Also, unable to do wrong, incapable of sin.
→Equally challenging synonyms of impeccable include unimpeachable and irreproachable. Challenging antonyms of impeccable include reprehensible, censurable (SEN-shur-uh-buul), and culpable (KUHL-puh-buul).
Earlier in this level I told you about the prefix in-, which may mean “in” or “into” or have a privative function, depriving or taking away the meaning of what follows. Impeccable combines this privative prefix in-, meaning “not,” with the Latin peccare, to make a mistake, do wrong, blunder, sin. By derivation, impeccable means not able to make a mistake, incapable of sinning or doing wrong; hence, perfect, faultless.
Now, if you’ve been reading carefully I bet you’re wondering why in the world I’m talking about the prefix in- when the prefix in impeccable is im-. Well, my verbally advantaged friend, your exemplary guide through the oddities of the English language has the answer, and here it is:
When the prefix in- is attached to a word beginning with the letter b, p, or m, the n changes to an m. Thus, imbalanced means not balanced; impossible means not possible; and immutable means not mutable, not changeable, fixed. Similarly, when the prefix inappears before a word beginning with l or r, the n changes to an l or an r: illogical means not logical; irreproachable means not reproachable, without fault or blame, and therefore impeccable, perfect, flawless.
So now that you know how the spelling of the prefix in- changes, I suppose you’re wondering why it changes. The answer is simple: ease of pronunciation. If we had to say in peccable and in reproachable, it would be not only in logical but also nearly in possible. The altered spelling of the prefix makes these and dozens of other words easier to pronounce.
Now let’s take a look at the closely related words impeccable, immaculate, and infallible, all of which employ the privative prefix in-, meaning not.
The adjective fallible comes from the Latin verb fallere, to deceive, lead astray, cause to make a mistake. In modern usage fallible means capable of error or likely to be wrong, as human beings are fallible creatures. Attach the prefix in- to fallible and you have the word infallible, not fallible, not capable of making an error, unable to fail. As your infallible guide through Verbal Advantage, I assure you that this program is an infallible method of building your vocabulary.
The unusual noun macula (MAK-yuh-luh) means a spot or stain. Its direct Latin root, macula, meant either a physical spot or blotch or a moral blemish, a stain on one’s character. In current usage macula refers specifically either to a blemish on the skin or to a sunspot; the corresponding adjective maculate means stained, blemished, impure, corrupt. Attach the prefix in- to the adjective maculate and you have the word immaculate, not maculate, unstained, spotless. An immaculate house is spick-and-span; an immaculate complexion has no blemishes; an immaculate reputation or background is spotless, clean as a whistle. In Roman Catholicism, the Immaculate Conception is the doctrine that the Virgin Mary was miraculously conceived without the moral stain of original sin.
And now for our keyword, impeccable. From its Latin root, peccare, to make a mistake, blunder, sin, English has also inherited three other words: the noun peccadillo (PEK-uh-DIL-oh) means a small sin, minor fault or flaw; the adjective peccant (PEKint) means guilty, sinful, culpable; and the adjective peccable (PEK-uh-buul) means liable to sin or do wrong. Slap the privative prefix in- onto the unfortunate peccable and you have its more pleasant antonym, impeccable, incapable of sin, unable to do wrong, and therefore free from all faults or imperfections. Impeccable taste is faultless; impeccable speech is flawless; an impeccable performance is perfect.