It's the E in "e Equals Mc2"
This page is the CodyCross answer for the clue below from Larger than Life, Group 2157, Puzzle 2 (Garage Doors).
Question is: It's the E in "e Equals Mc2"
and the answer is: ENERGY
Word Meaning:
ENERGY — The impetus behind all motion and all activity.
Definitions from Wiktionary.