Yerok

The letter yer (Ъ, ъ, italics Ъ, ъ) of the Cyrillic script, also spelled jer or er, is known as the hard sign (твёрдый знак ) in the modern Russian and Rusyn alphabets and as er golyam (ер голям, "big er") in the Bulgarian alphabet. The letter is called back yer in the pre-reform Russian orthography, in Old Russian, and in Old Church Slavonic. Originally the yer denoted an ultra-short or reduced middle rounded vowel. Its companion is the front yer, now known as the soft sign in Russian and as er malək (ер малък, "small er") in Bulgarian (Ь, ь), which was originally also a reduced vowel, more frontal than the ъ, and which is today used to mark the palatalization of consonants in all of the Slavic languages written in the Cyrillic script, except for Serbian and Macedonian, where it is not used although its traces can be seen in the letters њ and љ. The two reduced vowels together are called the yers in Slavic philology.