Hangul Syllable Deulm

With -ㅁ nominalizer, the sentence supplies the meaning. In 생각이 듦, a thought comes to mind; elsewhere read whichever sense of 들다 fits.

As of 2026-09-08, no separate invention story for this block was documented: it is 들- plus native -ㅁ. That ending is old, seen in fourteenth-century gugyeol and fifteenth- and sixteenth-century Hangul, with -음 covering both uses by the late sixteenth century. Hangeul itself was created in 1443 and explained in 1446 to write Korean accessibly.