say it: in-tur-AK-shuhn
interaction is a noun meaning "a mutual or reciprocal action; interacting". It carries 2 recorded senses.
a mutual or reciprocal action; interacting
(physics) the transfer of energy between elementary particles or between an elementary particle and a field or between fields; mediated by gauge bosons
physics
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 interaction 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.