N3 - 単位たんい
unit, denomination, credit (in school)
N3 - 単語たんご
word, vocabulary, (usually) single-character word
N3 - 単なるたんなる
mere, simple, sheer
N3 - 単にたんに
simply, merely, only, solely
N2 - 単数たんすう
singular (number)
N1 - 単一たんいつ
single, simple, sole, individual, unitory
N1 - 単調たんちょう
monotony, monotone, dullness
N1 - 単独たんどく
sole, independence, single, solo (flight)
N1 - 単ひとえ
one layer, single