須

Originally a pictographic character.

In oracle-bone inscriptions, 須 depicted a person with facial hair, representing beard / whiskers.

Thus, the original meaning of 須 was “beard.”

Later, 須 was phonetic-loaned to express an abstract modal meaning “must,” “inevitably,” “it is required.”

As this abstract usage became dominant, the original concrete meaning (beard) was reassigned to:

鬚 — 須 + 髟 (hair)

During this transition, the graphic structure of 須 changed: the beard element became separated and the character came to resemble a compound of 彡 (hair-like strokes) + 頁 (head), giving it a misleading appearance as a ideographic compound.

Semantic development:

- concrete object — beard; facial hair

- grammatical borrowing — inevitability, necessity

- modal adverb — must; ought to

- abstract necessity — obligation, requirement

須 is a core modal marker in Classical and Modern Chinese, expressing necessity or obligation.

In Korean, 須 survives mainly in fixed compounds (필수) and literary phrasing.

Common compounds and constructions:

필수 (必須) — indispensable; required

수지 (須知) — matters that must be known

수요 (須要) — necessary; essential (classical)

수유 (須臾) — a brief moment (originally “must-be moment”)

Classical-style usage:

須當如此 — “it must be so”

不可不須 — “cannot but be necessary”

Unlike 必 (absolute certainty), 須 emphasizes situational or logical necessity.

Related characters (necessity & obligation):

必 — certainly; inevitably

當 — ought to; appropriate

要 — need; want

需 — require; demand

不可 — cannot; must not

Among these, 須 uniquely expresses logical or situational necessity rather than absolute certainty or desire.

In older Korean translations and educational texts, 須 was glossed as: 모로매, 모롬즉.

These forms derive from the Middle Korean root 모롬, meaning "inevitability · unavoidable necessity · oughtness."

Modern 모름지기 preserves this semantic lineage.