serti -ser- gismu

x1 are stairs/stairway/steps for climbing structure x2 with steps x3.

See also stapa, loldi, senta.

In notes:

loldi
x1 is a floor/bottom/ground of x2.
senta
x1 is a layer/stratum [shape/form] of x2 [material] within structure/continuum/composite x3.
stapa
x1 steps/treads on/in surface x2 using limbs x3.
rajyserti
se1=sr1 is a ladder / vertical stairway for climbing structure se2 with steps se3, vertical in reference frame sr2.