He didn't change the definition. Definitions always vary, and some are more accurate than others.

Humility is to do nothing out of selfish ambition, vainglory, or conceit. To regard and value others above yourself. To not be haughty or prideful or boastful.

To be humble doesn't mean having an artificially low view of yourself, but rather an honest view. To see ourselves as we truly are.

"For everyone who exalt himself will be humbled, and he who humbles himself will be exalted." Luke 14:11

"Before destruction a man's heart is haughty, but humility comes before honor" Proverbs 18:12

"The reward for humility and fear of the Lord is riches and honor and life" Proverbs 22:4