a day when something very unpleasant or sad happens.

A bomb went off early this morning. This is a black day for the peace process. (usually + for)

• put a damper on something
• put a foot wrong
• put a gun to head
• put a gun to someone's head
• put a lid on
• Put a lid on it!
• put a lid on something
• put all cards on the table
• put all eggs in one basket
• put all your cards on the table
• put all your eggs in one basket
• put an end to
• put an end to something
• put a premium on
• put a premium on something
• put a price on
• put a price on something
• put a price tag on
• put a price tag on something
• put a quart into a pint pot
• put a rocket under
• put a rocket under someone
• put aside
• put aside something
• Put a sock in it!