You can get Wordnet for many languages at GlobalWordnet
There is also BabelNet.
BabelNet is both a multilingual encyclopedic dictionary, with lexicographic and encyclopedic coverage of terms, and a semantic network which connects concepts and named entities in a very large network of semantic relations, made up of about 16 million entries, called Babel synsets.
BabelNet 4.0 covers 284 languages and is obtained from the automatic integration of:
This is an example of how to translate words with BabelNet in SPARQL.
There is the Open Multilingual Wordnet project by Francis Bond at Nanyang Technological University, Singapore. They have wordnets built from wiktionary and other resources for many languages under an open licence.