Library / English Dictionary

RA

Pronunciation (US):

(GB):

 I. (noun) 

Sense 1

Meaning:

(astronomy) the equatorial coordinate specifying the angle, measured eastward along the celestial equator, from the vernal equinox to the intersection of the hour circle that passes through an object in the sky; usually expressed in hours and minutes and seconds; used with declination to specify positions on the celestial sphere

Example:

one hour of right ascension equals fifteen degrees

Synonyms:

celestial longitude; RA; right ascension

Classified under:

Nouns denoting spatial position

Hypernyms ("RA" is a kind of...):

angular distance (the angular separation between two objects as perceived by an observer)

Domain category:

astronomy; uranology (the branch of physics that studies celestial bodies and the universe as a whole)

Sense 2

Meaning:

Ancient Egyptian sun god with the head of a hawk; a universal creator; he merged with the god Amen as Amen-Ra to become the king of the gods

Synonyms:

Ra; Re

Classified under:

Nouns denoting people

Instance hypernyms:

Egyptian deity (a deity worshipped by the ancient Egyptians)

Domain category:

antiquity (the historic period preceding the Middle Ages in Europe)

Sense 3

Meaning:

An intensely radioactive metallic element that occurs in minute amounts in uranium ores

Synonyms:

atomic number 88; Ra; radium

Classified under:

Nouns denoting substances

Hypernyms ("Ra" is a kind of...):

metal; metallic element (any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.)

Holonyms ("Ra" is a substance of...):

uranium ore (any ore from which uranium can be extracted)

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