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self-satisfaction; (self-)complacency; smugness
それはただの自己じこ満足まんぞくだ。
That's just self-satisfaction.
彼かれはただ自己じこ満足まんぞくしていただけだ。
He was just being self-satisfied.
一いち度どの勝利しょうりで自己じこ満足まんぞくに浸っひたってはいけない。
Don't get complacent after just one win.