microdot

noun

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

verb (used with object), mi·cro·dot·ted, mi·cro·dot·ting.

2. to make a microdot of.

noun

1. a microcopy about the size of a pinhead, used esp in espionage
2. a tiny tablet containing LSD