1 block, bar, check, prevent, stop (up), arrest, halt, clog, make impassable; bring to a standstill:
The vein is obstructed by a large blood clot. A clogged drain is obstructing the water.
2 hamper, slow, impede, interfere with, retard, hinder, interrupt, delay, stay, stall:
An overturned truck obstructed traffic on the motorway.
3 preclude, prevent, debar, block, prohibit, forbid, stop, stand in the way of:
They are manoeuvring to obstruct her from taking over the company.