The term shinai (kanji: 竹刀) means "bamboo sword" in English. It is written しない in hiragana. It's pronounced roughly like "she-nigh".
刀, by itself, is pronounced katanaKATANA 刀 "sword" learn more... in the Japanese reading. 竹, by itself, is pronounced take (tah-keh) in the Japanese reading. The shinai refers particularly to the bamboo sword used in kendoKENDO 剣道 "the way of the sword" learn more... training and contests.