say it: ak-tuh-VAY-shuhn
activation is a noun meaning "stimulation of activity in an organism or chemical". It carries 3 recorded senses.
stimulation of activity in an organism or chemical
the activity of causing to have energy and be active
making active and effective (as a bomb)
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 activation 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.