conjunction
even though it is not; despite not
Conjunction meaning 'even though it is not' or 'despite not'. Used to connect a negative supposition to a contrasting result. Often follows a noun or na-adjective stem with では/じゃ, or an i-adjective with くは. Related to まい, but まいに is a fixed form.
See also: まい
彼は専門家ではあるまいに、よく知っている。
Even though he is not an expert, he knows a lot.
簡単ではあるまいに、彼はすぐに解決した。
Despite it not being easy, he solved it quickly.