ProZ.com is a comprehensive resource for freelance professional translators-- among other things, it includes:
A search engine which provides translations of terms along with examples of their use in real-world contexts-- useful for seeing the various ways a word can be translated in context.
A website from the government of Canada which provides definitions and translations of terms from a wide variety of specialized fields. Most useful for French, though it does also have some Spanish terms.
Click here to browse books on translation in the Meredith Library catalog.