It merged with and eliminated the letter Fita (Ѳ) in the Russian alphabet in 1918.

The name of Ef in the Early Cyrillic alphabet is фрьтъ (fr̥tŭ or frĭtŭ), in later Church Slavonic and Russian form it became фертъ (fert).

In some instances in Latin, it represented historical th-fronting and derived from Proto-Indo-European *dʰ.

In the Germanic languages, the f sound arose from PIE *p via Grimm's law, which remained unchanged in Slavic.

The letter ф is thus almost exclusively found in words of foreign origin, especially Greek (from φ and sometimes from θ), Latin, French, German, Dutch, English, and Turkic languages Example borrowings in Russian: The few native Slavic words with this letter (in different languages) are examples of onomatopoeia (like Russian verbs фукать, фыркать etc.)