Tente esta consulta. Ele limitará os dados dos pais e unirá as tabelas
SELECT w.word,d.definition,d.pos FROM
(SELECT id, word FROM words ORDER BY id LIMIT 5) w
JOIN definition d ON d.wordid = w.id
SELECT w.word,d.definition,d.pos FROM
(SELECT id, word FROM words ORDER BY id LIMIT 5) w
JOIN definition d ON d.wordid = w.id