blocker

American  

[blok-er] / ˈblɒk ər /

noun

1. a person or thing that blocks.

2. Football. a player whose assignment or special skill is blocking.

3. Biochemistry. a substance that inhibits the physiological action of another substance, as the beta blocker propranolol that interferes with neurotransmitters in the sympathetic nervous system.

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blocker British  

/ ˈblɒkə /

noun

1. a person or thing that acts as a block

2. physiol an agent that blocks a physiological function, such as the transport of an ion across an ion channel

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Etymology

Origin of blocker

Middle English word dating back to 1200–50; see origin at block, -er ¹