A dictionary is a key/value data structure, just like a Hashtable. You can store your data on jar file as a Java properties file (http://docs.oracle.com/javase/tutorial/essential/environment/properties.html).
As Java ME does not have the java.util.Properties class you have to do the loading manually.
    public class Properties extends Hashtable {
        public Properties(InputStream in) throws IOException {
            if (in == null) {
                throw new IllegalArgumentException("in == null");
            }
            StringBuffer line = new StringBuffer();
            while (readLine(in, line)) {
                String s = line.toString().trim();
                if (s.startsWith("#") == false) {
                    int i = s.indexOf('=');
                    if (i > 0) {
                        String key = s.substring(0, i).trim();
                        String value = s.substring(i + 1).trim();
                        put(key, value);
                    }
                }
                line.setLength(0);
            }
        }
        private boolean readLine(InputStream in, StringBuffer line) throws IOException {
            int c = in.read();
            while (c != -1 && c != '\n') {
                line.append((char)c);
                c = in.read();
            }
            return c >= 0 || line.length() > 0;
        }
        public String get(String key) {
            return (String) super.get(key);
        }
    }
Here is a sample
    InputStream is = getClass().getResourceAsStream("/dictionary.properties");
    Properties dictionary = new Properties(is);