rebla -reb- gismu

x1 is a/the tail/appendix [body-part] of x2; [metaphor: trailing, following portion/appendage].

See also nalci, pimlu, se lidne, trixe, birka, jimca.

In notes:

birka
x1 is a/the arm [body-part] of x2; [metaphor: branch with strength].
jimca
x1 is a branch/bough/limb of x2; x2 forks into branches x1; [preferred over metaphorical birka].
lidne
x1 precedes/leads x2 in sequence x3; x1 is former/preceding/previous; x2 is latter/following.
nalci
x1 is a/the wing [body-part] of x2; [metaphor: lateral supporting surface].
pimlu
x1 is a/the feather/plume(s)/plumage [body-part] of animal/species x2.
trixe
x1 is posterior/behind/back/in the rear of x2 which faces/in-frame-of-reference x3.
brirebla
x1 is a bridi-tail of predicate relationship x2 with relation x3 among arguments (sequence/set) x4.
latyrebla
x1 is a cat tail of x2
rebdesygau
x1 wags their tail.
rebyrespa
r1 is a lizard of species r2.
bai'ei (exp!)
unary mathematical operator: successor/augment/increment (by one), succ(a) = a++ = a+1