Synonyms of soundly

2 Syllables
stably, ably, roundly, rightly, fully, smoothly, strongly, tightly, firmly
3 Syllables
correctly, splendidly, famously, durably, nicely, properly, closely, expertly, agreeably, thoroughly, profoundly, skillfully, adeptly, suitably, sanely
4 Syllables
carefully, favorably, capitally, commendably, reasonably, excellently, unshakeably, completely, proficiently, conscientiously, efficiently, competently, admirably, successfully
5 Syllables
irreproachably, accurately, attentively, effectively, adequately
6 Syllables
satisfactorily