Definition of substratum in US English:



  • 1An underlying layer or substance, in particular a layer of rock or soil beneath the surface of the ground.

    • ‘Paleocene fossil outcrops abound in the glauconite rich gray clay substrata of the creek banks exposed beneath the deep rich surface soils.’
    • ‘The acoustic facies of its substratum has neither the characteristics of the continental crust nor those of the oceanic crust.’
    • ‘Deep drilling in the southern Tyrrhenian Sea floor revealed a continental and oceanic substratum covered by upper Miocene and younger sedimentary successions.’
    • ‘For example, barnacles maintain a relatively large proportion of their total surface area in contact with the underlying substratum, and display body temperatures that are tightly coupled with ground temperature.’
    • ‘In recent habitats, Lyreidus does not inhabit shallow, inshore environments but, instead, is found in outer shelf and slope environments, generally on soft substrata.’
    1. 1.1 A foundation or basis of something.
      ‘there is a broad substratum of truth in it’
      • ‘The idea that Aboriginal culture is essentially unchanging and thus ‘the oldest in the world’ appeals to many Australians, and presumably strengthens the substratum of support for native title, as well as the Aboriginal art market.’
      • ‘His materials and settings are drawn from the substratum of his experience as a curator, trained in taxidermy, active in the conservation of paintings and the handling of fossils, fascinated by animal maquettes and mediaeval weapons.’
      • ‘They are part of the range of institutions that have been the substratum of Scottish distinctiveness within the UK.’
      • ‘They constitute the ideological substratum of the party and are not merely tactical considerations to wean away separatist support structures in the Valley as the Government of India tends to believe.’
      • ‘If there is a substratum underlying this trust it is that of a property trust in which units are issued to the public.’
      foot, lowest part, lowest point, base, extremity
      View synonyms


Mid 17th century: modern Latin, neuter past participle (used as a noun) of Latin substernere, from sub- ‘below’ + sternere ‘strew’. Compare with stratum.