Assibilation

Assibilation is when certain consonant sounds are pronounced with a hissing or a sibilant sound. This is like saying "sssss" or "shhhh" along with the consonant sound. For example, when you say "t" in the word "tip", your tongue touches the roof of your mouth to make the sound. But when you say "t" in the word "sit", your tongue is in the same position but you also add a hissing sound like "ssss" at the end, making it sound like "sitsss". This is assibilation. It happens with other consonant sounds too, like "d" turning into "dz" in words like "adventure." Basically, assibilation is when you make a consonant sound with a hissing sound added to it.