Impeccably means without a single flaw. Impeccably dressed, impeccably behaved, impeccably timed.
It belongs above all to manners and to dress, and impeccably dressed is the highest compliment of its kind. The Latin means without sin, which is a very grand origin for a word about a suit.
1adverbimpeccablyWithout a single flaw.
“The hotel room was impeccably clean, with fresh flowers on the table.”
impeccably is a manner.
Proto-Indo-European
*ped-
Latin
impeccabilis — not liable to sin
Middle French
impeccable
English
impeccable
English, today
impeccably
Built from
From impeccable + -ly. impeccable comes 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