Cusp and Tail end

Cusp noun - An interval of time just before the onset of something.

Tail end and cusp are semantically related. In some cases you can use "Tail end" instead a noun "Cusp".

Tail end noun - The part of the body upon which someone sits.

Cusp and tail end are semantically related. Sometimes you can use "Cusp" instead a noun phrase "Tail end".