faithfully
UK: ˈfeɪθ.fəl.i | US: ˈfeɪθ.fəl.i
adv. in a loyal and steadfast manner
adv. with accuracy or precision
adv. (in correspondence) used as a formal closing
Derived from Middle English feithful, combining "faith" (from Old French feid, Latin fides meaning "trust, loyalty") + the suffix "-ful" (Old English -full, meaning "full of"). The adverbial suffix "-ly" (Old English -līce) was added to form "faithfully." The word evolved from a concrete sense of loyalty (e.g., feudal oaths) to broader meanings of reliability and precision.
The knight served his king faithfully for decades.
She transcribed the document faithfully, without errors.
"Yours faithfully," he wrote at the end of the formal letter.
The old dog waited faithfully by the door for its owner.
The artist reproduced the landscape faithfully, capturing every detail.