تشدید

Also known as consonant length, long consonant, double consonant, geminated consonant, consonant elongation, geminate consonant

In phonetics and phonology, gemination (; from Latin 'doubling', itself from gemini 'twins'), or consonant lengthening, is an articulation of a consonant for a longer period of time than that of a singleton consonant. It is distinct from stress. Gemination is represented in many writing systems by a doubled letter and is often perceived as a doubling of the consonant. Some phonological theories use 'doubling' as a synonym for gemination, while others describe two distinct phenomena.