means The standard unit of electrical resistance, defined as the resistance through which one volt drives one ampere of current.

from Named for the German physicist Georg Simon Ohm, who in the 1820s worked out the relationship between voltage, current, and resistance now bottled as Ohm's law. His own name comes from the German vocabulary of older surnames, but it's his stubborn experiments with wires that got it stamped onto every circuit diagram. The unit was formally adopted in his honor later in the 19th century.