quadruple note

US /ˈkwɑː.drə.pəl ˌnoʊt/
UK /ˈkwɑː.drə.pəl ˌnoʊt/
"quadruple note" picture
1.

a musical note having the time value of four whole notes, represented by a large oval note head with two vertical lines on either side.

:
The composer used a quadruple note to indicate a very long duration in the slow movement.
The ancient manuscript showed several instances of the rare quadruple note.