Answer:

coo

Answer	Crossword Clue
COO	Co. bigwig
COO	Soft murmur
COO	Bit of sweet talk

COO	Pigeon English?
COO	Dove's sound
COO	Murmur
COO	Noise from a nest
COO	Aviary sound
COO	Corp. manager
COO	Pigeon's sound
COO	Dove bar?

COO	Speak lovingly
COO	Pigeon sound
COO	Something babies do (and people do at babies)
COO	Talk like one smitten
COO	Tender sound
COO	Managerial exec
COO	Whisper sweet nothings
COO	Sound that might be heard in a 16-Across

COO	Second-in-command at a corp.
COO	Lovey-dovey sound
COO	Company exec
COO	Baby's sound
COO	Gentle bird call
COO	Sound from a window ledge
COO	Say sweet words
COO	Bill's partner

COO	Sound of sweet nothings
COO	Bit of love talk
COO	Speak pigeon?
COO	Gentle murmur
COO	Cote call
COO	Bird call
COO	Some soft words
COO	Noise in a nest

COO	Engage in some pillow talk
COO	Murmur lovingly
COO	Bird sound
COO	Corp. manager of day-to-day affairs
COO	Talk as lovers do