/blok"euhr/ , n.
1. a person or thing that blocks.
2. Football. a player whose assignment or special skill is blocking.
3. Biochem. a substance that inhibits the physiological action of another substance, as the beta blocker propranolol that interferes with neurotransmitters in the sympathetic nervous system.
[ 1200-50; ME; see BLOCK, -ER 1 ]