Wiktionary
n. (''mostly British?'') a highly accurate multimeter having a deadbeat needle and anti-parallax mirror
Wikipedia
Avometer is a British trademark for a line of multimeters and electrical measuring instruments; the brand is now owned by the Megger Group Limited. The first Avometer was made by the Automatic Coil Winder and Electrical Equipment Co. in 1923, and measured direct voltage, direct current and resistance. Possibly the best known multimeter of the range was the Model 8, which was produced in various versions from the May 1951 until 2008; the last version was the Mark 7.
The multimeter is often called simply an AVO, because the company logo carries the first letters of 'amps', 'volts' and 'ohms'. The design concept is due to the Post Office engineer Donald Macadie, who at the time of the introduction of the original Avometer in 1923 was a senior officer in the Post Office Factories Department in London. Mr. MacAdie (1871 - 1955) was born in the county of Caithness in northern Scotland. (The local pronunciation of MacAdie rhymes with Caddy).