big word

noun2

1. •
   An erudite word, especially a Latinate or multisyllabic one; a word used by scholars, intellectuals, etc., but that is not commonly known outside of academia.

   • The customer complained that the instructions were incomprehensible, and our office tried to provide remedial help, but when they complained that “supplementary” and “atmospheric” were big words, we knew that they were beyond help.
2. •
   [in the plural] Boastful or exaggerated statements.

   • big words from a little man