飲のみ込こみが悪わるい

Meanings

1

expression, i-adjective

slow to understand; slow-witted

Describes a person who takes time to grasp or learn something. Often used in a mildly critical or self-deprecating way.

じ

分ぶん

は

飲の

み

込こ

み

が

悪わる

い

方ほう

だ

と

思おも

う

。

I think I'm on the slow side when it comes to understanding things.

飲のみ込こみが悪わるい
Standard kanji spelling using 飲.
呑のみ込こみが悪わるい
Variant using 呑, which can carry a nuance of swallowing whole or accepting readily.
のみ込こみが悪わるい
Kana spelling for the first part, common in casual writing.

飲のみ込こむ
The verb meaning 'to swallow' or 'to understand'; 飲み込みが悪い is the adjectival phrase describing poor understanding ability.
頭あたまが悪わるい
Means 'stupid' or 'unintelligent' more directly; 飲み込みが悪い focuses specifically on the speed of comprehension rather than overall intelligence.

From 飲み込む (to swallow; to understand) + が悪い (is bad), literally 'swallowing is bad', metaphorically extending to slow comprehension.