Certainly, there are many synonyms that can be used to replace the word "certainlies". Some of the possible synonym options include "definitely", "absolutely", "undoubtedly", "assuredly", "positively", "unquestionably", "indisputably", "clearly", "undeniably", "unequivocally", "conclusively", "surely", "confidently", and "firmly". Each of these words communicates a strong sense of certainty and confidence in the statement being made. Depending on the context and tone of the text, one synonym may be a better fit than another. However, all of these words can effectively convey a strong assertion and conviction.