Denshi Jisho — Online Japanese dictionary

万一 まんいち 1: emergency; unlikely event;
2: (Adverb) by some chance; by some possibility
Common word, Noun 
万一 ばんいち 1: emergency; unlikely event;
2: (Adverb) by some chance; by some possibility
Out-dated or obsolete kana, Noun 
万一 ばんいつ 1: emergency; unlikely event;
2: (Adverb) by some chance; by some possibility
Out-dated or obsolete kana, Noun 
万一 まんいつ 1: emergency; unlikely event;
2: (Adverb) by some chance; by some possibility
Out-dated or obsolete kana, Noun 
万一のため まんいちのため just in case
Expression 
万一に備える まんいちにそなえる to provide against contingencies
Ichidan verb 
万一を考える まんいちをかんがえる to be prepared for the worst
Expression, Ichidan verb 

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