What word or phrase does your mother always say?
1660s, echoic of doves; the phrase to bill and coo is first recorded 1816. Related: Cooing. The noun is recorded from 1729.
(written Cos in the R.V.), a small island, one of the Sporades in the Aegean Sea, in the north-west of Rhodes, off the coast of Caria. Paul on his return from his third missionary journey, passed the night here after sailing from Miletus (Acts 21:1). It is now called Stanchio.