I. ˈ ̷ ̷ˌ ̷ ̷ noun
Etymology: short (I) + stop (after the phrase stop short )
1. : a workman at a rod mill who diverts the rod for winding in a coil
2.
a. : the player position in baseball for defending the infield area to the third-base side of second base — see baseball illustration
b. : the player stationed in the shortstop position
3. : an agent that interrupts at some desired stage a polymerization reaction proceeding by way of radicals
II. transitive verb
: to cause (a polymerization reaction) to stop by adding a suitable chemical