How to say "crumble" in Japanese

• 崩れるくずれるJLPT N2approx.Common
  ichidan verb, intransitive verbThe default for physical crumbling: a wall, cliff, or building losing its shape and falling apart, or food such as a cookie breaking into soft pieces.
  本ほんの山やまは今いまにも崩くずれそうに見みえる。↗

  Those books look as if they're going to topple over any minute.
• くさるJLPT N3approx.Common
  godan verb, intransitive verbCrumbling through rot or corrosion: use it when wood rots, metal rusts, or stone weathers and falls apart. It is really about decay, not about structures collapsing.
• 砕けるくだけるJLPT N2approx.Common
  ichidan verb, intransitive verbReally 'to be smashed or shatter': choose it when something breaks into fragments rather than slowly crumbles; it also describes enthusiasm cooling.
• 倒れるたおれるJLPT N4approx.Common
  ichidan verb, intransitive verbPrimarily about falling or collapsing — a person, tree, building, or organization going down. Its 'crumble' sense is limited to being destroyed in a collapse, so it is seldom the word for gradual crumbling.

Use 「崩れる」 when something loses shape and falls apart, 「くさる」 for decay through rust or rot, 「砕ける」 for breaking into fragments or cooled enthusiasm, and 「倒れる」 for falling or being destroyed in a collapse.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 崩れるくずれるto collapse
• クランブルcrumble
• くさるto corrode
• 砕けるくだけるto collapse
• 倒れるたおれるto be destroyed (in a collapse)