to do or say something in order to make people stop arguing and become calmer.

She was furious with Dave for forgetting her birthday so I tried to pour oil on troubled waters by offering to take them both out for a meal.

• au courant
• au naturel
• autumn years
• avail of
• avail of something
• avail yourself of
• avail yourself of something
• avant-garde
• average out to
• average out to something
• a vicious circle
• a voice in the wilderness
• avoid like the plague
• avoid someone like the plague
• avoid something like the plague
• a volte-face
• a wake-up call
• a walk of life
• a war of nerves
• a war of words
• a waste of breath
• a watched pot never boils.
• a way of life
• a weak link
• a weak link in the chain