混じる
まじる · majiru · JLPT N3 · verb-godan
to mingle with
🀄 majiru sounds like mahjong: tiles get mixed and mingle together
混 means mix (Chinese hùn, as in 混合). 混じる is intransitive: things become mixed or mingle by themselves. Its transitive partner 混ぜる (mazeru) is what you do when you mix something.
混 — water radical 氵 + 昆 (kūn, phonetic)
A semantic-phonetic compound: 氵 (water) gives the meaning, while 昆 supplies the sound. The original sense was waters mingling or flowing together, which extended to 'mix, blend, confuse.' Modern uses like 混乱 (chaos) and 混合 (to mix) preserve this core idea of things merging.