to be difficult or impossible to find.

I don't know how you find anything in your desk, Polly. It's like looking for a needle in a haystack.

• mark my words.
• mark time
• mark up
• mark up something
• marriage made in heaven
• marry beneath station
• marry beneath your station
• Marry in haste, repent at leisure.
• mask slips
• match made in heaven
• match up
• match up against
• match up against someone
• matter in hand
• matter of
• matter of doing something
• matter of life and death
• matter of life or death
• matter of opinion
• matter of record
• matter of something
• matter of time
• max out
• max yourself out
• may as well