1 Syllableburn, churn, earn, fern, hern, kirn, learn, pirn, quern, spurn, stern, turn, urn
Now you can make multisyllabic rhymes in the new rhymit app :)
2 Syllablesadjourn, astern, casern, concern, discern, downturn, heartburn, lucerne, return, sunburn, unlearn
3 Syllablestaciturn, unconcern