say it: loo-muh-NES-uhns
luminescence is a noun meaning "light not due to incandescence; occurs at low temperatures". It carries 2 recorded senses.
light not due to incandescence; occurs at low temperatures
light from nonthermal sources
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 luminescence come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.