pacifier

n. placater, appeaser; mouthpiece with rubber nipple for babies to suck on

A pacifier or binky or piece (North American English), dummy (British, New Zealand, and Australian English) or soother (Canadian and Irish English), is a rubber, plastic, or silicone nipple given to an infant or other young child to suck upon.
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Noun
1. someone who tries to bring peace
(synonym) conciliator, make-peace, peacemaker, reconciler
(hypernym) mediator, go-between, intermediator, intermediary, intercessor
(hyponym) appeaser
(derivation) pacify
2. device used for an infant to suck or bite on
(synonym) comforter, baby's dummy, teething ring
(hypernym) device
(derivation) pacify, lenify, conciliate, assuage, appease, mollify, placate, gentle, gruntle

v. pacify, calm

ADJ
bringing peace| peaceful