with little or no sound
"the class was listening quietly and intently"
"she was crying quietly"
In a quiet manner.
"She whispered her secret to me quietly so no one else would hear."
The word quietly comes from Middle English, where it was formed by adding the suffix -ly to the adjective quiet. It entered modern usage as an adverb meaning "in a quiet manner," directly extending its original sense of silence or lack of noise.