This is the 8171st most frequent Japanese word.
山折
"Mountain fold" (a type of fold in paper origami where the crease forms a peak).
Here, '山折り' is described as one of two folding techniques, emphasizing its role in creating structures.
山折りと谷折りを組み合わせて形を作ります。
You combine mountain folds and valley folds to create shapes.
In this instance, '山折り' is referred to as a line indicating where to make this specific fold type.
彼は山折りの線を丁寧に引きました。
He carefully drew the mountain fold line.
In this sentence, '山折り' is used in the context of paper folding, indicating a fold that peaks upwards like a mountain.