cradle
A small rocking bed for a baby.
Cradle is a small bed designed for babies, usually with curved rockers on the bottom that let you gently rock it back and forth. The rocking motion soothes babies to sleep, which is why we use the phrase rock the cradle to describe caring for an infant. Parents have been using cradles for thousands of years because that gentle swaying motion calms fussy babies and helps them drift off.
The word also means the place where something begins or originates. Ancient Mesopotamia, between the Tigris and Euphrates rivers, is often called the cradle of civilization because that's where some of humanity's first cities, writing systems, and complex societies emerged. Greece is considered the cradle of democracy since that's where the idea of citizens voting on their government first developed. When you say New Orleans is the cradle of jazz, you mean that's where the musical form was born and first developed.
To cradle something (as a verb) means to hold it gently and protectively, the way you'd hold a baby or a fragile object. A football player might cradle the ball in his arms while running downfield. You might cradle a rescued baby bird in your cupped hands.