泌

A phono-semantic compound consisting of:

水 (water) — semantic component, indicating liquid or fluid;

必 (bì / pì) — phonetic component, providing the sound. The structure conveys liquid that inevitably emerges or flows, suggesting a natural or internal release.
Semantic development: - water flowing subtly; - liquid seeping or permeating; - internal secretion; - biological processes (glands, fluids). The meaning developed from gentle physical flow to internal biological function.

In Korean, 泌 is almost always read as “비” in standard vocabulary.

In personal names, both readings 비 and 필 are possible, though 필 is more common.

분비 (分泌) — secretion

침분비 (唾液分泌) — saliva secretion

泌 is strongly associated with biological and medical contexts, especially glandular activity. Compared to more general flow-related characters, 泌 conveys a quiet, internal, and continuous release rather than an outward or forceful flow.
Related characters: 瀉 — to discharge; to pour out

泄 — to leak

流 — to flow

滲 — to seep; to permeate

Among these, 泌 emphasizes internal, often controlled or natural secretion, especially in living organisms.