Burdensome, cumbersome, or causing hindrance; archaic form meaning the same as encumbering.
From encumber with -ous suffix (full of), an older adjective form that's largely been replaced by encumbering in modern English.
This is an archaic word you'll find in old literature—it means the same as 'cumbersome.' Shakespeare might have called heavy armor 'encumbrous,' but today we'd just say 'burdensome.'
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