obstruct (v.)

1610s, a back-formation from obstruction or else from Latin obstructus, past participle of obstruere "build up, block, block up, build against, stop, bar, hinder," from ob "in front of, in the way of" (see ob-) + struere "to pile, build" (from PIE *streu-, extended form of root *stere- "to spread"). Related: Obstructed; obstructing.