A grinch is someone who spoils other people's fun or enjoyment, especially during celebrations or happy occasions. The word comes from Dr. Seuss's famous character the Grinch, who tried to ruin Christmas for the Whos of Whoville by stealing their presents and decorations.

When someone acts like a grinch, they complain about things others are excited about or try to dampen the mood. If your class is buzzing with excitement about the upcoming field trip and one student keeps saying it will probably be boring and terrible, that student is being a grinch. If someone grumbles about holiday music or tells younger kids that their Halloween costumes are silly, they're acting grinchy.

The word carries a slightly playful tone. Calling someone a grinch is gentler than calling them mean or cruel. It suggests they're being unnecessarily negative but could probably snap out of it if they tried. In Dr. Seuss's story, even the Grinch's heart eventually grew three sizes when he realized what really mattered about Christmas. When someone accuses you of being a grinch, they're usually hoping you'll stop complaining and join in the fun.