WordNet sense 1 (when a wrestler's shoulders are forced to the mat):

fall

WordNet sense 2 (small markers inserted into a surface to mark scores or define locations etc.):

peg

WordNet sense 3 (a number you choose and use to gain access to various accounts):

personal identification number, PIN number

WordNet sense 4 (informal terms of the leg):

stick

WordNet sense 5 (axis consisting of a short shaft that supports something that turns):

pivot

WordNet sense 6 (flagpole used to mark the position of the hole on a golf green):

flag

WordNet sense 7 (a holder attached to the gunwale of a boat that holds the oar in place and acts as a fulcrum for rowing):

oarlock, thole, tholepin, rowlock

WordNet sense 8 (a club-shaped wooden object used in bowling; set up in triangular groups of ten as the target):

bowling pin

WordNet sense 9 (to hold fast or prevent from moving):

immobilize, trap, immobilise