Currently, only Set and Collection are supported.
You must also use a Java generic as the EJB 3.0 deployer looks at the type of the generic to determin the other side of the OneToMany relationship.
So, it should be
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY) @JoinColumn(name = "language_oid") public Set<Word> getWords() { return words; } public void setWords(Set<Word> value) { words = value; }