The most common and most likely answer to this crossword clue is the 11 letter word TERMINOLOGY
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The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
Crossword Answer definitions
TERMINOLOGY noun- The doctrine of terms; a theory of terms or appellations; a treatise on terms, a system of specialized terms.
- The set of terms actually used in any business, art, science, or the like; nomenclature; technical terms.