pivot word
/ˈpɪvət ˌwəːd/noun
1A word crucial to the meaning or structure of a sentence, paragraph, etc.
2The word on which a pivot-pun turns.
- Chamberlain seems not to have used pivot-word..
3 Linguistics. Any of a set of words used at an early stage of a child's acquisition of language as central items to which other words are attached.
Origin
Mid 19th century; earliest use found in The Times. From pivot + word.