This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

ad. Significantly; to a degree worth considering.

ad. In a manner or to a degree not trifling or unimportant; greatly; much.

In a degree deserving notice; in a degree not trifling or unimportant.

ad. to a great extent or degree

"Sometimes it's a tradeoff - for example, cars have resulted in considerably cleaner and less smelly streets than horse-drawn carriages, but they created their own pollution and severe political problems."

greatly    much