say it: IN-sest
incest is a noun meaning "sexual intercourse between persons too closely related to marry (as between a parent and a child)". It carries one recorded sense.
sexual intercourse between persons too closely related to marry (as between a parent and a child)
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 incest 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.