Definition from Wiktionary, the free dictionary
ѳ (lower case, upper case Ѳ)
- (obsolete) Letter fita (in Russian: фита́ f (fitá) or spelled ѳита́ f (fitá) before 1917 reform). Consonantal letter intended to represent the sound /θ/ but was replaced as /f/. Replaced by the letter ф (f) (f) or т (t) (t) in the spelling reform of 1917.