soundest
sound-est
adjective
Most logical, sensible, or well-founded.
"This is the soundest plan we have."
adjective
Most healthy, strong, or free from defect.
"They chose the soundest timber for the roof."
adjective
Most deep and undisturbed (referring to sleep).
"She had the soundest sleep in ages."
Thesaurus
Synonyms: sound, good, healthy, strait, strong, phone, speech sound, substantial, solid, effectual, legal, valid