expression
indiscriminately; without distinction; heedless of
Used when someone acts without considering differences, boundaries, or consequences. Often followed by verbs like 使う, 食べる, 信じる, or 攻撃する.
彼は見境なしにお金を使ってしまう。
He spends money indiscriminately.
空腹だったので、見境なしに食べてしまった。
I was so hungry that I ate everything without thinking.
From 見境 (みさかい, 'distinction' or 'discernment') + なし (without) + に (adverbial particle). The phrase literally means 'without making distinctions'.