a problem or difficulty that is likely to happen in the future.

For farmers, another cloud on the horizon is higher prices for fertilizer and fuel.

Even when everything is going perfectly, Bruce can see dark clouds on the horizon.

Related vocabulary: on the horizon

• a bad apple
• a bad egg
• a bad workman blames his tools.
• a bag lady
• a bag of bones
• a baker's dozen
• a balancing act
• a ball and chain
• a ball-breaker
• a ballpark estimate
• a ballpark figure
• a balls-up
• a banana republic
• a banana skin
• a Band-Aid
• a bang up job
• a baptism by fire
• a baptism of fire
• a bargaining chip
• a basket case
• a battle of nerves
• a battle of wills
• a battle of wits
• ABCs of
• ABCs of something