Strong's #3174: megethos (pronounced meg'-eth-os)
 from 3173; magnitude (figuratively):--greatness.
Thayer's Greek Lexicon:
 ́ 
 
  megethos 
 
 1) greatness
 
  Part of Speech: noun neuter
Relation: from G3173
  Citing in TDNT: 4:544, 573
 
Usage:
This word is used 1 times:
Ephesians 1:19: "what is the exceeding  greatness of his power to us-ward"