sincerely

UK: sɪnˈsɪəli | US: sɪnˈsɪrli

Definition
  1. adv. in a genuine, honest, or heartfelt manner

  2. adv. (in letter closings) a conventional expression of earnest goodwill

Structure
sincere <genuine>ly <adverb suffix>
Etymology

The word "sincerely" derives from the Latin sincerus ("pure, clean, genuine"), possibly from sin- (without) + cera (wax), referring to unadulterated honey or untainted objects. Over time, sincere in English came to mean "free from deceit," and the adverbial suffix -ly was added to form "sincerely," emphasizing truthful expression. The term became standard in letter closings during the 18th century as a polite convention.

Examples
  1. She apologized sincerely for her mistake.

  2. The artist spoke sincerely about his creative process.

  3. "Yours sincerely" is a common closing in formal letters.

  4. He sincerely believed in the cause he was supporting.

  5. They thanked their guests sincerely for attending the event.