Persian Grammar
Learn About Persian Language

Gemination is the doubling of a consonant sound. A geminated consonant is articulated for a longer period of time than that of a single consonant. In English, gemination does not occur within words but for example in "calm man", you can see that the consonant m is geminated.

In Persian script, gemination is marked by placing the diacritic تشدید (tashdid) over the geminated consonant. You have to memorize words having gemination because tashdid is not normally written. When Persian is written in a Latin alphabet, gemination can be denoted with double consonants (as in Italian). For example, in najjâr (نجار) the two j's fall into separate syllables and therefore, the word is pronounced as "naj-jâr":

Word Syllables
ammâ امّا am-mâ
pelle پلّه pel-le
najjâr نجّار naj-jâr
jallâd جلّاد jal-lâd
khayyât خیّاط khay-yât

When double consonants occur at word final, they don't fall into separate syllables and are pronounced as one sound:

Word Syllables
khatt (line) خطّ khatt
khatti (linear) خطّی khat-ti