Defile
Part of speech: noun
Definition: A way or gorge so narrow that only one person at a time can pass.
Part of speech: verb
Definition: to make impure; to make dirty. Less strong than to pollute (intransitive) To march in a single file.
Befoul
Part of speech: verb
Definition: To make foul; to soil.To entangle or run against so as to impede motion.