Cinder

The lecture was a cinder, with the professor droning on about a dry topic.

The play was a cinder, and the actors seemed uninterested.

The once-bustling downtown area had become a cinder, with boarded-up shops and empty sidewalks.

His presentation was a cinder, and no one paid attention.

The relationship was a cinder, with no sparks or passion left.

The cinder blocks were used to build the foundation of the house.