microdot

American  

[mahy-kruh-dot] / ˈmaɪ krəˌdɒt /

noun

1. a photograph reduced to the size of a printed period, used especially to transmit messages, photographs, drawings, etc.

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verb (used with object)

microdotted, microdotting

1. to make a microdot of.

microdot British  

/ ˈmaɪkrəʊˌdɒt /

noun

1. a microcopy about the size of a pinhead, used esp in espionage

2. a tiny tablet containing LSD

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Etymology

Origin of microdot

First recorded in 1945–50; micro- + dot ¹

Example Sentences

Police are also using forensics to track stolen sheep, while Cumbrian sheep and beef farmer Pip Simpson has trialled coded microdots on the sheep's fleece to brand his sheep.

From BBC

Tradespeople may also install covert cameras in vans, apply forensic marking products such as microdots to their tools, and label them as protected, for example.

From BBC

Rare cycads are now sprayed with microdot paint that leaves invisible, individualised markers of a plant’s provenance.

From Economist

Those looking to understand the roots of San Francisco psychedelic rock need only read one observation from Paul Kantner, who died Thursday at age 74, to connect the microdots. 

From Los Angeles Times

There was also steganography, the art of shrinking and concealing information inside objects such as microdots, usually only detectable by those who knew exactly where to look.

From BBC