Imprescindible (en. Essential)

/im-pre-sin-ˈdi-ble/

Slang Meanings

Something that is absolutely necessary in an informal conversation.
That app is indispensable for students.
Esa aplicación es imprescindible para los estudiantes.
It is used to refer to someone who is key in a social group.
She is the indispensable one of the team; she cannot be missing.
Ella es la imprescindible del equipo, no puede faltar.