substratal

WordReference Random House Learner's Dictionary of American English © 2026

sub•stra•tum /ˈsʌbˌstreɪtəm, -ˌstrætəm, sʌbˈstreɪtəm, -ˈstrætəm/   n. [countable] , pl. -stra•ta /-ˌstreɪtə, -ˌstrætə, -ˈstreɪtə, -ˈstrætə/  -stra•tums. 

1. something spread or laid under something else.
2. something that is under something else or serves as a foundation.

See -strat-.

WordReference Random House Unabridged Dictionary of American English © 2026

sub•stra•tum  (sub′strā′təm, -strat′əm, sub strā′təm, -strat′əm), n., pl. -stra•ta (-strā′tə, -strat′ə, -strā′tə, -strat′ə), - stra•tums. 

1. something that is spread or laid under something else;
   a stratum or layer lying under another.
2. something that underlies or serves as a basis or foundation.
3. [Agric.] the subsoil.
4. Ecology, Laboratory [Biol.] the base or material on which a nonmotile organism lives or grows.
5. Philosophy substance, considered as that which supports accidents or attributes.
6. Photography a layer of material placed directly on a film or plate as a foundation for the sensitive emulsion.
7. Linguistics [Historical Ling.] a set of features of a language traceable to the influence of an earlier language that it has replaced, esp. among a subjugated population:
   The French word for 80,
   quatre-vingts ("four twenties''), may reflect a Celtic substratum. Cf. superstratum. 

• Neo-Latin; see sub-, stratum
• 1625–35

sub•stra′tive, sub•stra′tal, adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

substratum / sʌbˈstrɑːtəm -ˈstreɪ-/ noun ( -strata / -ˈstrɑːtə -ˈstreɪtə/)

1. any layer or stratum lying underneath another
2. a basis or foundation; groundwork

Etymology: 17th Century: from New Latin, from Latin substrātus strewn beneath, from substernere to spread under, from sub- + sternere to spread

subˈstrative, subˈstratal adjective