|Noah Webster's Dictionary|
1. (v. i.) To make a low repeated cry or sound, like the characteristic note of pigeons or doves.
2. (v. i.) To show affection; to act in a loving way. See under Bill.
Coo (1 Occurrence)
Isaiah 59:11 We make a noise as bears -- all of us, And as doves we coo sorely; We wait for judgment, and there is none, For salvation -- it hath been far from us. (YLT)