impedance

noun

im·​ped·​ance im-ˈpē-dᵊn(t)s 

: something that impedes : hindrance: such as

a

: the apparent opposition in an electrical circuit to the flow of an alternating current that is analogous to the actual electrical resistance to a direct current and that is the ratio of effective electromotive force to the effective current

b

: the ratio of the pressure to the volume displacement at a given surface in a sound-transmitting medium

Examples of impedance in a Sentence

Recent Examples on the Web

Measuring electrical impedance at the plant stem, a device transmits data to a receiver placed at the base of the plant—which infers water levbels and needs of the plant. —IEEE Spectrum, 16 Jan. 2024

There's also bioelectrical impedance, which models the body as five cylinders of mass (the trunk and four limbs) and estimates body fat mass. —Kevin Purdy, Ars Technica, 14 June 2023

The sensor measures the electrical impedance of the plant stem, which indirectly measures moisture in the plant based on ions and conductivity. —IEEE Spectrum, 16 Jan. 2024

That enabled Smith and his cohorts to record the vocal tract impedance in different configurations in the mouth. —Elizabeth Rayne, Ars Technica, 29 Dec. 2023

Bioelectrical impedance analysis, which uses electric signals to tell fat from muscle in the body, is becoming more common in medical offices. —Lydia Denworth, Scientific American, 14 Dec. 2023

So by applying a current to a plant and measuring the resulting voltage, and then calculating the impedance (voltage divided by current), researchers can assess whether a plant has a healthy level of hydration. —IEEE Spectrum, 11 Dec. 2023

Comparing these readings with imaging, soil moisture, and leaf relative water content backed up the impedance measurements. —IEEE Spectrum, 11 Dec. 2023

The company’s audio engineers chose this combination of metals to maintain signal integrity thanks to an extremely low impedance. —Mark Sparrow, Forbes, 14 Feb. 2023

Word History

First Known Use

1886, in the meaning defined above

Medical Definition

impedance

noun

im·​ped·​ance im-ˈpēd-ᵊn(t)s 

1

: the apparent opposition in an electrical circuit to the flow of an alternating current that is analogous to the actual electrical resistance to a direct current and that is the ratio of effective electromotive force to the effective current

2

: the ratio of the pressure to the volume displacement at a given surface in a sound-transmitting medium

3

: opposition to blood flow in the circulatory system