Nintendo (任天堂) = 任 (nin) "leave to / entrust" + 天 (ten) "heaven / sky" + 堂 (dō) "hall / temple / company."
"Leave luck to heaven" or "Heaven blesses hard work."
In Japanese business names, dō (堂) conveys tradition and permanence (e.g., Shiseidō, Mitsukoshidō). Nintendo = "The Hall of Leaving Luck to Heaven."
Not "Nin-Ten-Do" as separate words — it's a compound with cultural weight.