Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
decryption is a noun meaning "the activity of making clear or converting from code into plain text". It carries one recorded sense.
the activity of making clear or converting from code into plain text
“a secret key or password is required for decryption”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for decryption come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.