a serious conversation between two people in which they talk honestly about their feelings.

We had a real heart-to-heart and we're getting on much better now.

• a dead ringer for
• a dead ringer for someone
• a dead ringer for something
• a dead weight
• a Dear John letter
• a death blow
• a death trap
• a designated driver
• a deus ex machina
• adhere to
• adhere to something
• ad hoc
• a diamond in the rough
• a different ball of wax
• a dime a dozen
• ad infinitum
• a dirty old man
• a dirty trick
• a dirty weekend
• a dirty word
• a disaster area
• ad nauseam
• a dog and pony show
• a dog in the manger
• a dog's breakfast