In traditional (Church Slavonic) typefaces, the central line is typically about twice the width of the letter's body and has serifs similar to those on the letterТ:. Sometimes the line is drawn as low as the baseline, which makes the letter difficult to distinguish fromД.
The traditional Russian name of the letter isфита́fitá (or, in pre-1918 spelling, ѳита́). Fita was mainly used to write proper names and loanwords derived from or via Greek.Russians pronounced these names with the sound/f/ instead of/θ/ (like the pronunciation of⟨th⟩ in "thin"), for example "Theodore" was pronounced as "Feodor" (now "Fyodor").
Early texts inRussian (and in the Russian recension ofChurch Slavonic) demonstrate an increasing interchangeability of Ѳ and Ф. Some scribes preferred one of the two letters and ignored the other. There existed an orthographical system to write Ѳ in an initial position and Ф elsewhere. Since the middle of the 17th century, selection between Ѳ and Ф was re-adjusted to exactly follow the Greek origin, the system still in use in Church Slavonic orthography.
In the first variant of the Petrine Russian alphabet (1707–1708), the letter Ф was eliminated and Fita became the only way to represent/f/. Later (1710) the letter Ф (with the same etymological rule of spelling Ѳ and Ф) was restored and both letters co-existed until the1918 spelling reform, when Fita was eliminated and replaced by the letterEf (Ф ф).
Many Greek words with Theta were adopted in Russian withTe (Т т) instead of Fita (mostly through Latin or other Western European languages): теорема (theorem), атлетъ (athlete), пантера (panther), фталевый (phthalic), etc. Sometimes dual spellings/pronunciations existed: ѳеатръ/театръ (theatre), аѳеизмъ/атеизмъ (atheism), алгориѳмъ/алгоритмъ (algorithm), каѳолическій/католическій (Catholic), etc.; the variants with Fita (in modern spelling with Ф) are typically more archaic or special.
In other languages which use the Cyrillic alphabet, Fita was pronounced/t/ and was replaced withTe (Т т). For example, the Bulgarian, Macedonian and Serbian version of Theodore is ТодорTodor or ТеодорTeodor.[citation needed]