Definitions

1. noun

A person who spoils or ruins a party or other social event by being a nuisance or causing trouble.

“The marplot in the wedding had a loud argument with the best man, causing the whole evening to go awry.”

2. verb

To spoil or ruin a party or other social event by being a nuisance or causing trouble.

“She went home early when her friend started to marplot at the party.”