Brilliant business name based on the word "define".
The word "definely" contains eight letters and three syllables. Established brands using three syllable names include Heineken, Verizon and Delicious.
Definely.com is a .com domain. Dot com domains are the most valuable top-level-domain in the world, famously used by websites like twitter.com. A .com is the first thing people think of when they think of a website.