Curtsy vs. Courtesy
Dam vs. Damn
Data vs. Datum
Days vs. Daze
Dazzled vs. Dazed
Diseased vs. Deceased
Deer vs. Dear
Defective vs. Deficient
Defendable vs. Defensible
Defensive vs. Defendable
Definitive vs. Definite
Defuse vs. Diffuse
Delegate vs. Relegate
Demur vs. Demure
Depraved vs. Deprived
Deprecate vs. Depreciate
Depredation vs. Deprivation
Desert vs. Dessert
Device vs. Devise
Diagnosis vs. Prognosis