通

to pass through;
to communicate, to be well connected;
to match in mind or intention;

Etymology

It is a phono-semantic compound, consisting of:

辵 (chwak/착, “to walk slowly, to go”) as the semantic element;

甬 (yong, “tube, narrow passage”) as the phonetic element.

In traditional village schools (서당), student performance was graded as 대통 (大通), 통 (通), 약통 (若通), 조통 (粗通), 불통 (不通). Here, 통 (通) was below 대통 (A) but above 약통 (C) — roughly equivalent to a B grade today.

In Middle Korean, the gloss (훈) for 通 was “ᄉᆞᄆᆞᆾ다” (“to penetrate, to reach fully”). This expression has since disappeared, but its derivative survives in modern Korean as 사무치다 (“to pierce deeply, to touch profoundly”).

Additionally, combined with the old verb “ᄢᅦ다” (“to pierce, to thread”), the compound expression “ᄢᅦᄉᆞᄆᆞᆾ다” meant “to penetrate, to pass through thoroughly.”