konju -kon-ko'u- gismu

x₁ is a cone [shape/form] of material x₂ with vertex x₃.

Also ellipse, ellipsoid (= konclupa). See also jesni, djine, sovda, kojna, jganu.

In notes:

djine: x₁ is a ring/annulus/torus/circle [shape/form] of material x₂, inside diam. x₃, outside diam. x₄.
jesni: x₁ is a needle [pointed shape/form, not tool] of material x₂.
jganu: x₁ is an angle [2-dimensional shape/form] from vertex x₂ subtended by lateral [segment] x₃.
kojna: x₁ is a corner/point/at-least-3-dimensional [solid] angle [shape/form] in/on x₂, of material x₃.
sovda: x₁ is an egg/ovum/sperm/pollen/gamete of/from organism [mother/father] x₂.
konclupa: c₁=k₁ is an ellipsoid [shape/form] of material c₂=k₂.
kubyko'u: x₁ is a pyramid of materal x₂ with vertex x₃