certissima
certissima is a Latin form of certus, meaning “certain, sure; fixed”. It is the nominative singular feminine superlative adjective.
Found 38 times in the Latin texts on Socratos.
Where it is used
Cicero, In C. Verrem 2.1.62: … orum quam adventus sui vestigia reliquerit? sed ego omnia quae negari poterunt praetermittam; etiam haec quae certissima sunt et clarissima relinquam; unum aliquod de nefariis istius factis eligam, quo facilius ad Siciliam possim …
Seneca the Younger, Oedipus 682: Certissima est regnare cupienti via
All forms of certus (declension table)
Source: Socratos (socratos.org), a free reader for Ancient Greek and Latin. Grammar from the Perseus Treebank and Morpheus; dictionary entries from Lewis & Short, A Latin Dictionary (Perseus Digital Library, CC BY-SA). Counts are from the texts on Socratos.