It is a Japanese word and in the phonetics of that language there is a sound that is described in English as the sound of "TS". The T is very subtle and is a short sound just before the s sound. It is formed by placing your tongue at the front of the roof of your mouth while you begin to say the "S" sound.
tsunami
chocolate
The spelling tsunami has a silent T (Japanese word meaning "harbor wave").
tsunami
T
The most known are tsar (czar) and tsunami.
Yes, the word "potpourri" does have a silent 't.' The 't' is not pronounced in the standard English pronunciation of the word. The word originates from French, where the 't' is also silent.
The T is there because it is pronounced "tsunami", not "sunami", in its original language. If you choose not to pronounce the T in your language/dialect, that's fine. It is correctly pronounced as Tzunami, with a clear 'z'.
Yes, in the word 'glisten' the 't' is silent.
The 't' is silent.
The word often is an antonym (opposite) of seldom, and has a silent 't'.
The t is silent in whistling.