sepli -sep-sei- gismu

x1 is apart/separate from x2, separated by partition/wall/gap/interval/separating medium x3.

Also aloof (= jiksei); alone (= rolsmisei meaning apart or unlike all others of its kind; pavysei, seirpavmei meaning "only" or "one alone" - do not use when talking about, for example, two people who are alone); x3 space. See also bitmu, snuji, senta, fendi, curve, jinsa, bitmu, marbi.

In notes:

bitmu
x1 is a wall/fence separating x2 and x3 (unordered) of/in structure x4.
curve
x1 is pure/unadulterated/unmitigated/simple in property x2 (ka).
fendi
x1 (agent) divides/partitions/separates x2 into sections/parts/ind. x3 by method/partition x4.
jinsa
x1 (object) is clean/pure of material/contaminant/dirt x2 by standard x3.
marbi
x1 is a shelter/haven/refuge/retreat/harbor for/protecting x2 from danger/threat x3.
senta
x1 is a layer/stratum [shape/form] of x2 [material] within structure/continuum/composite x3.
snuji
x1 is a sandwich/layering [not restricted to food] of x2 sandwiched between x3.
i'i
attitudinal: togetherness - privacy.
fesyseigau
x1 removes waste/trash x2 from x3.
pevyplu
x1 is like an island in a sea of x2; x1 is very distinct/foreign (in appearance, composition and/or behavior) from surroundings/environment/background x2.
sepcau
s1 is immediately next to x2.
sepygau
x1=g1 separates/puts distance/barrier(s) between x2=s1 and x3=s2.
sezyseigau
x1 separates/removes themself from x2 by gap/interval/partition/barrier x3.
temsepcau
c1=s1 is immediately next to s2 in time.
tersei
x1 is the spatial distance between x2 and x3