凹む

Verb derived from noun 凹 / 窪 (kubo, “an indentation, a depression”) + verbalizing suffix ぶ (bu, “becoming like ”),^[1] with suffix ぶ (bu) mutating to む (mu) due to the preceding syllable ぼ (bo).

• 窪む

• (Tokyo) くぼむ (Heiban – )^[2]
• IPA^(key):

凹(くぼ)む • (kubomu) intransitive godan (stem 凹(くぼ)み (kubomi), past 凹(くぼ)んだ (kubonda))

1. to become hollow, cave in, sink in

The transitive form is 凹める / 窪める (kubomeru). Consequently, the potential form is the same as the passive form, くぼまれる (kubomareru), instead of くぼめる (kubomeru) as shown in the table above.

The spelling 窪む is used more often for くぼむ, because the alternative spelling 凹む can also be read as へこむ (see below).

/herikomu/ → /hekomu/

Contraction of 減りこむ (herikomu), itself a compound of 減り (heri, “lessening, becoming less”, the 連用形 (ren'yōkei, “continuative or stem form”) of verb 減る heru, “to reduce, to become less”) +‎ 込む (komu, “to go inwardly”).^[1]

• (Tokyo) へこむ (Heiban – )^[2]
• IPA^(key):

凹(へこ)む • (hekomu) intransitive godan (stem 凹(へこ)み (hekomi), past 凹(へこ)んだ (hekonda))

1. to become hollow, cave in, sink in: see the kubomu reading above
2. to decline below a certain point, to become less
3. to be stuck to be at a loss: see 困る (komaru).
4. to yield, to submit
5. (informal) to be bummed out

   うまくできなくて凹(へこ)む

   umaku dekinakute hekomu

   to fail to do it well and get bummed out