obstruction (n.) Look up obstruction at Dictionary.com
1530s, from Latin obstructionem (nominative obstructio) "an obstruction, barrier, a building up," noun of action from past participle stem of obstruere "build up, block, block up, build against, stop, bar, hinder," from ob "against" (see ob-) + struere "to pile, build" (see structure (n.)).