Meod means very, exceedingly, greatly, or much. It appears about 300 times. It intensifies whatever it modifies. In the Shema it is translated 'strength' or 'might.'
In Deuteronomy 6:5, loving God with all your meod adds totality of effort to the love command — heart, soul, and strength. God deserves not merely love but love to the uttermost degree. Everything about God is meod — exceedingly great.