What is another word for were certain of?
Pronunciation: [wɜː sˈɜːtən ɒv] (IPA) 
When we are absolutely sure about something, we often use the phrase 'were certain of'. But there are many other synonyms that can convey the same level of confidence and certainty. For example, we can use 'convinced' to express our innermost belief about something. Alternatively, we can use 'positive' or 'confident' to emphasize the degree of certainty. 'Assured', 'guaranteed', 'settled', 'resolved', 'decided', and 'determined' are also some words that signify a high degree of certainty. We can use any of these synonyms depending on the context and the tone we want to convey, but all of them indicate a strong sense of conviction in our beliefs.
