overthrustPronunciation: /ˈəʊvəθrʌst/ GeologyDefinition of overthrust noun [mass noun] the thrust of one series of rock strata over another, especially along a fault line at a shallow angle to the horizontal. verb (past and past participle overthrust) [with object] force (a body of rock) over another: (as noun overthrusting)the increased overburden resulting from overthrustingoverthrust in other Oxford dictionaries Definition of overthrust in the US English dictionary