WordNet sense 1 (a three-dimensional shape with six square or rectangular sides):

cube, cube

WordNet sense 2 (a rectangular area in a city surrounded by streets and usually containing several buildings):

city block

WordNet sense 3 (an inability to remember or think of something you normally can do; often caused by emotional tension):

mental block

WordNet sense 4 (a simple machine consisting of a wheel with a groove in which a rope can run to change the direction or point of application of a force applied to the rope):

pulley, pulley-block

WordNet sense 5 (a metal casting containing the cylinders and cooling ducts of an engine):

engine block, cylinder block

WordNet sense 6 (an obstruction in a pipe or tube):

blockage, closure, occlusion, stop, stoppage

WordNet sense 7 (stop from happening or developing):

halt, kibosh

WordNet sense 8 (hinder or prevent the progress or accomplishment of):

blockade, embarrass, hinder, obstruct, stymie, stymy, hinder

WordNet sense 9 (a platform from which an auctioneer sells):

auction block

WordNet sense 10 (obstruct):

lug, stuff, choke up

WordNet sense 11 (render unsuitable for passage):

bar, barricade, block off, block up

WordNet sense 12 (block passage through):

impede, jam, occlude, obturate, close up

WordNet sense 13 (impede the movement of (an opponent or a ball)):

deflect, parry

WordNet sense 14 (be unable to remember):

forget, blank out, draw a blank

WordNet sense 15 (the act of obstructing or deflecting someone's movements):

blocking

WordNet sense 16 (prohibit the conversion or use of (assets)):

freeze, immobilize, immobilise