OneWorld Dictionary 1.0

OneWorld Dictionary by Ascendo is a leading multilingual reference tool for Apple desktops.
The free version is a good starting point for beginners.

It includes over 100,000 translations from English to Spanish, French, German and Italian.

Each language pair is comprised of over 250,000 translations. Translations include multiple meanings, part of speech, noun gender and verb tenses. One World Dictionaries integrate with Lion applications such as Safari so you can lookup words using control-click.