Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
prehistorical is an adjective meaning "belonging to or existing in times before recorded history". It carries one recorded sense.
belonging to or existing in times before recorded history
“prehistoric settlements”
“prehistoric peoples”
Definitions, synonyms and semantic relations for prehistorical come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.