Kernel sentence

~noun

Entry: a sentence (as "John is big" or "John has a book") exemplifying in a language one of a very small group of the grammatically simplest sentence types or patterns (as noun phrase + be + adjective  phrase or noun phrase + verb + noun phrase) which in transformational grammar are the basic stock from which all sentences in that language are derived and in terms of which they can all ultimately be described.

@ Milton-Kindersley Advanced Dictionary