stizu -tiz- gismu

x₁ is a chair/stool/seat/bench, a piece or portion of a piece of furniture intended for sitting.

In notes:

ckana: x₁ is a bed/pallet of material x₂ for holding/supporting x₃ (person/object/event).
jubme: x₁ is a table/flat solid upper surface of material x₂, supported by legs/base/pedestal x₃.
nilce: x₁ [furniture items] furnishes x₂ [location] serving purpose/function x₃.
zutse: x₁ sits [assumes sitting position] on surface x₂.
pesai (comp!): restrictive relative phrase marker: semi-permanently associated to; will remain associated unless something breaks that relation
birstizu: s₁ is an armchair.
nolstizu: s₁ is a throne/ceremonial chair used by noble/aristocratic/elite/high-born/titled in/under culture/society/standard n₂.
tsestu: s₁=z₂ is a seat for s₂=z₂.
amfite'atro: x₁ is an amphitheater, an oval or round structure having tiers of seats rising outward from a central arena
dalmasi: x₁ is a saddle on mount x₂