1an alternate/classical form of '混じる'; to be mixed in with or to blend with. Often appears in literary or older texts.
古文では「混ずる」と書かれることが多いが、現代語では「混じる」が一般的だ。
In classical texts it's often written as '混ずる', but in modern Japanese '混じる' is more common.
釉薬に青が混ずって、独特の色合いが出た。
Blue was mixed into the glaze, producing a distinctive hue.
彼の言葉にはいつも冗談が混ずって聞こえる。
His words always seem to have jokes mixed in.