The Collaborative International Dictionary of English v.0.48:
Block \Block\ (bl[o^]k), v. t. [imp. & p. p. Blocked
(bl[o^]kt); p. pr. & vb. n. Blocking.] [Cf. F. bloquer, fr.
bloc block. See Block, n.]
1. To obstruct so as to prevent passage or progress; to
prevent passage from, through, or into, by obstructing the
way; -- used both of persons and things; -- often followed
by up; as, to block up a road or harbor; to block an
entrance.
[1913 Webster]
With moles . . . would block the port. --Rowe.
[1913 Webster]
A city . . . besieged and blocked about. --Milton.
[1913 Webster]
2. To secure or support by means of blocks; to secure, as two
boards at their angles of intersection, by pieces of wood
glued to each.
[1913 Webster]
3. To shape on, or stamp with, a block; as, to block a hat.
[1913 Webster]
4. to cause (any activity) to halt by creating an
obstruction; as, to block a nerve impulse; to block a
biochemical reaction with a drug.
[PJC]
To block out, to begin to reduce to shape; to mark out
roughly; to lay out; to outline; as, to block out a plan.
[1913 Webster]