c. 1400 of a tool, c. 1600 of a person, agent noun from block (v.1). The U.S. football sense is from 1914.
Entries linking to blocker
block v.1
"obstruct, hinder passage from or to," 1590s, from French bloquer "to block, stop up," from Old French bloc "log, block of wood" (see block (n.1)). Compare Dutch blokkeren, German blockieren "to blockade." The sense in cricket is from 1772; in U.S. football, "stop or obstruct another player," from 1889. Related: Blocked; blocking.