Today it means: An instrument for detecting or measuring minute extension or movements of solid bodies. It consists of a small rod or disk of carbon forming part of an electrical circuit, whose resistance (varied by the changes of pressure produced by the movements of the object to be measured) causes variations in the strength of the current, which are indicated by a sensitive galvanometer. Full definition →
From Ancient Greek τάσις (tásis, “stretching, extension”) + -meter.
Ancient Greekτάσις all →
Etymology from Wiktionary, CC BY-SA 4.0.