Taoiseach is an Irish word that means "chief" or "leader". The term Taoiseach is used as the name of the Prime Minister and head of government of the Republic of Ireland. The current Taoiseach is Micheál Martin.
The correct pronunciation of Taoiseach in Irish is Tee-shahk. The greatest challenge in how you pronounce Taoiseach is the final part of the word, transcribed as -ahk. The sound that is produced in this part is often heard in Hebrew and resembles the sound you make when you prepare to spit. However unelegant that may sound, it is probably the best approximation of how to pronounce the end of Taoiseach.