People or devices that rock or hold something gently in a cradling motion, like someone rocking a baby's cradle.
From 'cradle' (a swinging bed for babies) + '-er' (one who does), forming a noun for those who perform the action of cradling. A straightforward occupational or descriptive term.
In old nurseries, professional 'cradlers' were sometimes employed—women whose only job was rocking babies to sleep!
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