Misspelling or variant of encyclopaedic (comprehensive, covering diverse subjects like an encyclopedia).
This appears to be a typographical variant or misspelling where 'y' has been inserted, creating an impossible pronunciation cluster. It does not represent a recognized word variant in either British or American English.
Even in the chaotic world of word variants, 'encydlopaedic' doesn't exist—this is pure typo, showing how standardized even obscure encyclopedia-related terms have become.
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