Dictionary.com
Thesaurus.com

double modal

American  

noun

  1. a syntactic construction in which two modal auxiliaries occur consecutively within a clause, as might could in I might could help you.

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.