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dull; uninteresting; boring; tedious
insignificant; unimportant; trifling; trivial; worthless
absurd; foolish; silly; stupid
useless; pointless; disappointing
つまらないことで怒らないで。
Don't get angry over trivial things.
つまらないものですがどうぞ。
It's nothing much, but please accept it.
あの本はつまらなくて最後まで読めなかった。
That book was so boring I couldn't finish it.