ETYM From Bib, v., because the bib receives the drink that the child slavers from the mouth.
1. A napkin tied under the chin a child while eating.
2. Top part; covering the chest.
1. A cloth or plastic shield tied under the chin to protect the clothes.
2. The part of an apron or of overalls extending above the waist.
3. A patch of differently colored feathers or fur immediately below the bill or chin of a bird or mammal.

1 Bible
2 biblical

Drink.