c. 1300, mageste, "greatness or grandeur of exalted rank or character, imposing loftiness, stateliness, qualities appropriate to rulership," from Old French majeste "grandeur, nobility" (12c.), from Latin maiestatem (nominative maiestas) "greatness, dignity, elevation, honor, excellence," from stem of maior (neuter maius), comparative of magnus "great, large, big" (of size), "abundant" (of quantity), "great, considerable" (of value), "strong, powerful" (of force); of persons, "elder, aged," also, figuratively, "great, mighty, grand, important," from suffixed form of PIE root *meg- "great."
Earliest English use is with reference to God or Christ; as a title of address or dignity to kings and queens (late 14c.), it is from Romance languages and originated in the Roman Empire.
It forms all or part of: acromegaly; Almagest; Charlemagne; maestro; magisterial; magistral; magistrate; Magna Carta; magnate; magnitude; magnum; magnanimity; magnanimous; magni-; Magnificat; magnificence; magnificent; magnify; magniloquence; magniloquent; Magnus; maharajah; maharishi; mahatma; Mahayana; Maia; majesty; major; major-domo; majority; majuscule; master; maxim; maximum; may (v.2) "to take part in May Day festivities;" May; mayor; mega-; megalo-; mickle; Mister; mistral; mistress; much; omega.
It is the hypothetical source of/evidence for its existence is provided by: Armenian mets "great;" Sanskrit mahat- "great, mazah- "greatness;" Avestan mazant- "great;" Hittite mekkish "great, large;" Greek megas "great, large;" Latin magnus "great, large, much, abundant," major "greater," maximus "greatest;" Middle Irish mag, maignech "great, large;" Middle Welsh meith "long, great."
c. 1500, "loftiness, height," from French grandeur, from Old French grandor "size, height, extent, magnitude; greatness" (12c.), from grand "great" (see grand (adj.)). "Being a word of late adoption, it retains the Fr. form -eur of the suffix." Extended sense of "majesty, stateliness" in English is first recorded 1660s.
a name of God in the Bible, c. 1600, from Hebrew, plural (of majesty?) of Eloh "God" (cognate with Allah), a word of unknown etymology, perhaps an augmentation of El "God," also of unknown origin. Generally taken as singular, the use of this word instead of Yahveh is taken by biblical scholars as an important clue to authorship in the Old Testament, hence Elohist (1830; Elohistic is from 1841), title of the supposed writer of passages of the Pentateuch where the word is used.
mid-14c., nobilite, "honor, renown; majesty, grandeur;" late 14c., "quality of being excellent or rare," from Old French nobilite "high rank; dignity, grace; great deed" (12c., Modern French nobilité), and directly from Latin nobilitatem (nominative nobilitas) "celebrity, fame; high birth; excellence, superiority; the nobles," from nobilis "well-known, prominent" (see noble (adj.)).
Meaning "quality of being of noble rank or birth; social or political preeminence, usually accompanied by hereditary privilege" is attested from late 14c.; sense of "the noble class collectively" is from late 14c. Sense of "dignity of mind, elevation of the soul, loftiness of tone" is from 1590s.