med dgag phyang chad

indispensable; x med thabs med do dgos dus dran par gyis this is indispensable-remembering it whenever you need it [RY]

indispensable, essential, impossible to do without [RY]

med thabs med pa (to be) indispensable/ sine qua non/ inevitable; cannot be omitted [RB]

indispensable, essential, impossible to do w/ o [IW]