The Collaborative International Dictionary of English v.0.48:

Ra \Ra\ (r[aum]), n.
   A roe; a deer. [Obs.] --Chaucer.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Ra- \Ra-\
   A prefix, from the Latin re and ad combined, coming to us
   through the French and Italian. See Re-, and Ad-.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Ra
    n 1: an intensely radioactive metallic element that occurs in
         minute amounts in uranium ores [syn: radium, Ra,
         atomic number 88]
    2: 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 [syn: Ra, Re]
    3: (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; "one hour of right
       ascension equals fifteen degrees" [syn: right ascension,
       RA, celestial longitude]

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "Ra":
   Amen-Ra, Anubis, Apollo, Bast, Helios, Horus, Hyperion, Isis, Khem,
   Min, Neph, Nephthys, Nut, Osiris, Phoebus, Phoebus Apollo, Ptah,
   Savitar, Set, Shamash, Sol, Surya, Thoth, Titan



V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

RA
       Real Address (Power4, IBM, CPU)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

RA
       Registration Authority (PKI, ITU, cryptography)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

RA
       Remote Access (BBS)