pin drop

Noun

pin-drop (plural pin-drops)

1. (figuratively, idiomatic) The sound of a small metal pin dropping onto the ground or a floor; notable because a falling pin makes almost no sound when it hits the ground except for when a setting is so quiet that even the smallest, negligible noise would be noticeable.
   • Like a pin-drop in a deep ocean, the news of Amos Tutuola's death came quite unceremoniously to Nigerians early this week. His passage became almost unnoticed [...]1999, Owomoyela, Oyekan, chapter 7, in Amos Tutuola revisited, page 147
2. A small increment or amount.
   • He made two preparations: one pin-drop of blood on one slide, and a lump the size of a pea spread thin on another.1940, A. Roothaert, dutch vet, page 404

See all 4 meanings of pin-drop