Definition of "trad"
adjective:
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Short for traditional, referring to an older or original style, especially in the phrase trad jazz.
from Wiktionary, Creative Commons Attribution/Share-Alike License -
Short for traditional, used in lieu of the name of the composer of a piece of music, whose real name is lost in the mists of time.
from Wiktionary, Creative Commons Attribution/Share-Alike License
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