NinjaWords is an online dictionary which claims it is "… fast like a Ninja."

Ninjas are three things:

1. They're smart
2. They're accurate
3. They're really fast

Ninjawords is based on these principles.

Give it a try at http://ninjawords.com/.

Some tips to use it even faster

You can compare definitions by looking up many words on the same page.

• Type them one by one and hit enter, or type them all at once in the search box, separated by commas.