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