A comprehensive treatise or compendium, especially referring to Ptolemy's famous astronomical work 'Almagest,' which was the primary source for astronomy for over 1,400 years.
From Arabic 'al-majisti' (the greatest), which is how Islamic scholars referred to Ptolemy's 'Syntaxis Mathematica.' The Arabic honorific became the work's common name when it was rediscovered in Europe during the Renaissance.
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