Merriam-Webster's Collegiate® Dictionary, 11th Edition
TACKLE
I. noun
Etymology: Middle English takel; akin to Middle Dutch takel ship's rigging
Date: 13th century
a set of the equipment used in a particular activity ; gear ,
2. a ship's rigging, an assemblage of ropes and pulleys arranged to gain mechanical advantage for hoisting and pulling,
3. the act or an instance of tackling, b. either of two offensive football players positioned on each side of the center and between guard and end, either of two football players positioned on the inside of a defensive line,
II. verb (tackled; tackling)
Date: 1600
transitive verb to attach or secure with or as if with tackle,
2. to seize, take hold of, or grapple with especially with the intention of stopping or subduing, to seize and throw down or stop (an opposing player with the ball) in football, to set about dealing with , intransitive verb to tackle an opposing player in football, tackler noun