without distinction; indiscriminately
Used to describe doing something without differentiating between categories, people, or things. Often appears in negative contexts or when emphasizing equality of treatment.
He is kind to everyone, without distinction of age or gender.
This machine treats all parts the same, without distinguishing by color.
Combination of 区別 (distinction) + the negative form of する (せず) + the particle に, forming an adverbial phrase meaning 'without distinguishing'.