plano-, plan-, plani-

(Latin: flat, even, level, smooth)

explain
explainable (adjective), more explainable, most explainable
Disposed to being understood or interpretable: Kitty had an explainable reason for being late for school which her mother accounted for in the written excuse for her teacher, Mrs. Jones.
explainer
explanation
explanatory
pedoplania
Flattening of the foot or feet.
plain
plainly
plalnicaudate
Having a flat tail, as certain reptiles.
plan
plane
planer
planicipital
Having a flat head, as an insect; flat-headed.
planidorsate
Having a flat back.
planifolious
Having or consisting of flat leaves; applied to composite flowers consisting wholly of ligulate florets.