sip, drink, suck
歠 centers on taking in liquid in small amounts: sipping, drinking, or sucking. The meanings all describe a gentle, gradual intake rather than gulping.
歠 is a rare character. It appears to combine 酉 (wine vessel) with 欠 (open mouth) and other elements, suggesting drinking or sipping from a vessel. The exact historical development is uncertain.
The left side resembles a wine vessel 酉 with extra strokes, and the right side has an open mouth 欠. Picture someone tilting a small cup to their lips and taking a tiny sip.
For セツ, imagine sipping a hot drink in a quiet setting: the soft sound 'sets' cues セツ as you take a small sip.