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Meaning & use

umbra

noun·Advancedtechnical

Last updated

UK/ˈʌmbrə/
US/ˈʌmbrə/

Meanings

  1. nouncountabletechnical

    The darkest central part of a shadow, where the light source is completely hidden from view.

    Grammar: Plural umbras or umbrae: the umbra of the Moon.

    Patterns

    • the umbra of something
    • inside the umbra

    People standing inside the Moon's umbra saw the Sun vanish completely.

    The umbra of the tree was so dark that the grass beneath it stayed cool.

    In the diagram, the umbra is shaded black and the penumbra gray.

  2. nouncountabletechnical

    The dark central area of a sunspot, surrounded by a lighter outer ring.

    Grammar: Astronomy sense; contrasted with the penumbra of the same sunspot.

    Patterns

    • the umbra of a sunspot

    The sunspot's umbra looks nearly black through a solar telescope.

    Astronomers measured the temperature of the umbra and found it cooler than the surrounding surface.

Word forms

pluralumbras
plural (Latin)umbrae

Common combinations

lunar umbra
The Moon entered Earth's lunar umbra, causing a total eclipse.
umbra and penumbra
Students drew the umbra and penumbra on the worksheet.
the Moon's umbra
The Moon's umbra sweeps across the land at high speed.
within the umbra
Observers within the umbra saw totality.
umbra shadow
The umbra shadow of the planet stretches far into space.

Synonyms and how they differ

full shadow
Full shadow is a plainer phrase for the same region, but umbra is the precise term in science.
core shadow
Core shadow is sometimes used in art and photography for the darkest part of a shadow on an object, while umbra implies a light source completely blocked.

Opposites

penumbra

Word family

penumbra noun
The lighter outer part of a shadow where light is only partly blocked.
umbral adjective
Relating to an umbra or shadow.
antumbra noun
The area beyond the umbra's tip where an annular eclipse is seen.
umbrella noun
Shares the Latin root umbra ('shade'); originally something that gave shade.

Commonly confused: umbra or penumbra? umbra or umbrella?

umbra vs penumbra

The penumbra is the partly lit outer region of a shadow; the umbra is the completely dark center.

umbra vs umbrella

An umbrella is a rain or sun shade; umbra is the dark part of a shadow.

Practice

During a total solar eclipse, observers standing in the Moon's ______ see the Sun completely covered.

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