Denshi Jisho — Online Japanese dictionary

れい zero; nought
Common word, Noun, No-adjective 
ぜろ zero; nought
Noun, No-adjective 
ひれい non-zero
No-adjective, Mathematical term 
きんれい nilpotent
Na-adjective 
べきれい nilpotent
No-adjective, Mathematical term 

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