- a combining form meaning “seven,” used in the formation of compound words: septilateral.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
before a vowel sept-
from Latin septem
Word Origin and History for septi-
before vowels sept-, word-forming element meaning "seven," from Latin septem (see seven).
Online Etymology Dictionary, © 2010 Douglas Harper