In Old French, the noun combre meant a defensive
obstacle formed by felled trees with sharpened branches facing the enemy.
Later, in Middle French, combre referred to a barrier, similar to a dam or
weir, constructed in the bed of a river to hold back fish or protect the banks.
That notion of holding back is what informs our verb encumber. One can be
physically encumbered (as by a heavy load or severe weather) or figuratively
(as by bureaucratic restrictions). Combre also gives us the adjectives
cumbersome and cumbrous, both meaning "awkward or difficult to
handle."