The spelling and pronunciation of "wast diffuse" may seem confusing at first glance. The word "wast" is spelled with a silent "e" at the end, as it is a past tense form of the verb "to be". The pronunciation is /wɒst/ or "wahst". As for "diffuse", the "ff" is pronounced as a single "f" sound, making the pronunciation /dɪˈfjuːz/. So, "wast diffuse" is pronounced as /wɒst dɪˈfjuːz/ or "wahst dih-FYOOS".