expression
to anyone; to whomever; indiscriminately
Used adverbially to mean 'without distinction of person', often implying openness or lack of selectivity. Common in phrases like 誰彼なしに話しかける (talk to anyone and everyone).
彼は誰彼なしに声をかける。
He talks to anyone and everyone.
誰彼なしに秘密を話してはいけない。
Don't tell secrets to just anybody.
From 誰彼 (anyone) + なしに (without), literally 'without distinguishing who is who'.