irregularity; unevenness; bumpiness
Colloquial noun describing a surface or shape that is not flat or smooth, with protruding and recessed parts. Often used for roads, walls, or physical objects.
This road is very uneven and hard to walk on.
Fill the irregularities in the wall with putty.
Derived from the verbs 出っ込む (でっこむ, to protrude) and 引っ込む (ひっこむ, to recede), combined into a compound noun. The exact historical derivation is uncertain, but it is a colloquial formation.