Shaddah
Shaddah (Arabic: شَدّة shaddah [ˈʃæd.dæ], '[sign of] emphasis', also called by the verbal noun from the same root, tashdid تشديد tashdīd 'emphasis') is one of the diacritics used with the Arabic alphabet, indicating a geminated (long) consonant. It is functionally equivalent to writing a consonant twice in the orthographies of languages like Latin, Italian, Swedish, and Ancient Greek, and is rendered as such in Latin script in most schemes of Arabic transliteration, e.g. رُمّان = rummān 'pomegranates'.