Syntactic gemination, or syntactic doubling, is an external sandhi phenomenon in Italian and some other Western Romance languages. It consists in the lengthening (gemination) of the initial consonant after words of certain categories.
The phenomenon is variously referred to in the English language as word-initial gemination, phonosyntactic consonantal gemination, as well as under the native Italian terms: raddoppiamento sintattico (RS), raddoppiamento fonosintattico (RF), raddoppiamento iniziale, rafforzamento iniziale (della consonante)
In standard Italian, syntactic doubling occurs after the following words (with exceptions described below):