-fest

WordReference Random House Learner's Dictionary of American English © 2025

-fest, suffix. 

1. -fest is attached to nouns to form nouns with the meaning "an assembly of people engaged in a common activity'' named by the first element of the compound:
   gab + -fest → gabfest (= group of people gabbing or talking a lot);
   song + -fest → songfest (= assembly of people singing together).

WordReference Random House Unabridged Dictionary of American English © 2025

-fest, 

1. a combining form occurring in compound words that have the general sense "an assembly of people engaged in a common activity'';
   the first element of the compound usually specifies the activity:
   gabfest;
   slugfest;
   songfest.

• German Fest festival, holiday (see feast), as in Sängerfest choral festival