say it: HAHR-duh-ning
hardening is a noun meaning "abnormal hardening or thickening of tissue". It carries 3 recorded senses.
abnormal hardening or thickening of tissue
the process of becoming hard or solid by cooling or drying or crystallization
“the hardening of concrete”
“he tested the set of the glue”
the act of making something harder (firmer or tighter or more compact)
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 hardening 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.