冒頭【ぼうとう】
beginning, opening, start, outset
冒険【ぼうけん】
adventure, venture, venture which is unlikely to succeed, risky attempt, danger, hazard, risk
冒す【おかす】
to brave, to risk, to face, to venture, to harm, to afflict, to affect, to desecrate, to profane, to assume (someone else's surname), to take