Something humdrum is dull, tedious, and totally boring. If a regular old photography class sounds too humdrum, you might instead sign up for Underwater Photography of Marine Predators. Don't forget your wetsuit!
Anything that you can call humdrum is so severely lacking in variety and excitement that it's sure to make you hum and drum your fingers out of boredom. Humdrum is an adjective to describe the unglamorous monotony of everyday routines. It's the same old thing, again and again, over and over. Humdrum can also mean predictable, mind-numbing and not very challenging — hopefully the complete opposite of your social life.