The term ninjutsu (kanji: 忍術) means "the skill of prowling" in English. It is written にんじゅつ in hiragana. It's pronounced roughly like "neen-jute-sue".
Literally, the skill of prowling about. 忍 is the same nin that is used in ninjaNINJA 忍者 "stalking/hiding person" learn more... (忍者, “one who prowls about”). This kanji is used more frequently as the verb shinobu (忍ぶ), hence the alternate term for ninja, shinobiSHINOBI 忍 "ninja [literally stalking or hiding]" learn more.... The primary meaning is to bear something (setbacks, suffering, etc.) in a stoical manner.
術 means skill or art. It is seldom used on its own, at least in everyday Japanese. You will find it, for example, in the word for surgery (手術, shujutsu, “skill of the hands”) and in the word for the fine arts (美術, bijutsu, “skill in the beautiful”). The Japanese reading of 術 is sube, which can be translated as means (to an end).