a rounded bowl or basin, including the bowl-shaped cap of a pillar and the oil reservoir of a lampstand
The core idea is shape: a rounded, open basin. The same word names three very different objects in the Hebrew Bible, and what ties them together is their curved, bowl-like form:
- the golden bowl of Ecclesiastes 12:6, a rounded vessel whose shattering pictures the end of life
- the reservoir of oil on top of the golden lampstand in Zechariah's vision, feeding the lamps
- the rounded cap crowning each of the two bronze pillars that stood before Solomon's temple
So the word is defined by form rather than by use. When it names the top of a pillar, it points to a specific feature: the rounded swelling at the very top of the column, not the whole ornamented capital. A related vessel word, מִזְרָק, by contrast is defined by what it is for, dashing liquid in worship, rather than by its shape.