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. block.

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; block, -er ¹

Example Sentences

A caveat to keep in mind is that ExpressVPN’s ad blocker only works with the Lightway protocol.

From Salon • Mar. 13, 2026

This helps teams identify which defenders are most worth neutralising with a blocker.

From BBC • Mar. 8, 2026

It might — though there’s a major potential blocker I’ll get to in a moment.

From MarketWatch • Feb. 10, 2026

For those at risk of preterm labor, a PIEZO1 blocker, if developed, could work alongside current medications that relax uterine muscle by limiting calcium entry into cells.

From Science Daily • Jan. 13, 2026

He could hit like a locomotive and was a devastating blocker.

From "October Sky" by Homer Hickam