Fortition is a consonant mutation in which a sound is changed from one considered "weak" to one considered "strong" – the opposite of lenition. Although less frequent than lenition in the languages of the world, word-initial and word-final fortition is not uncommon. Italian, for example, presents numerous regular examples of word-initial fortition both historically (Lat. Januarius with initial /j/ > gennaio, with ) and synchronically (e.g. /ˈkasa/ "house, home" → but /a ˈkasa/ "at home" → ). Catalan is among numerous Romance languages with diachronic word-final devoicing (frigidus > */ˈfɾɛd/ > . Fortition also occur in Catalan for /b d ɡ/ in consonant clusters with a lateral consonant (Lat. populus > poble or . Word-medially, /lː/ is subject to fortition in numerous Romance languages, ranging from in many speech types on Italian soil to in some varieties of Spanish.
Read more about this topic: Lenition