half mast 
noun
1The position of a flag which is being flown some way below the top of its staff as a mark of respect for a person who has died: each club flew its flag at half mast...
- A council spokesman said: ‘We will be asking employees to observe the three minutes silence and we will have our flags at half mast as marks of respect.’
- At the plant, which remained closed yesterday, two orange TCL flags were flown at half mast, as a mark of respect for the two lives which were lost.
- Flags were flying at half mast as a mark of respect for the Duke of Norfolk who died two days ago at the age of 86, the Arundel ground being part of the Duke's estate.
1.1chiefly humorous A position lower than normal or acceptable, especially for clothes: his tie was at half mast...
- It was a man whose pants were baggy with a zipper at half-mast.
- it was well into the evening and my tie was at half mast.