What is the difference between "predominantly" and "predominately". Are they both similar?
Yes - they are both adverbs, but the difference is where they come from - predominate and predominant. Both these, and the adverb forms, date from the late 1500s. Predominantly is more common than predominately, (as predominant is than predominate), although there is no difference in meaning between the two, and neither form is incorrect - just different!