- a combining form meaning “long,” used in the formation of compound words: longicorn.
Origin of longi-
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Word Origin and History for longi-
word-forming element meaning "long," from Latin longi-, comb. form of longus (see long (adj.)).
Online Etymology Dictionary, © 2010 Douglas Harper