つまずく
つまずく · tsumazuku · JLPT N2 · verb-godan
to trip
🦶 躓 = 足 (foot) + 質: a foot catches on something solid and you lurch forward
The kanji 躓 pairs the foot radical 足 with 質, so the word is about a foot meeting an obstacle. Everyday text usually writes it in kana as つまずく.