Rigor is something strict, severe or demanding. 1  Harsh and strict treatment in the military for cadets is an example of rigor. 2  Freezing weather and ice are examples of the rigors of winter.  Difficult and challenging academic courses are an example of academic rigor.
The suffix gram means to draw or write. This is used in telegram.
The gram (abbreviation, g or gm) is the cgs (centimeter/gram/second) unit of mass. A force of one dyne (1 dyn), applied to a mass of one gram (1 g), will cause that mass to accelerate at one centimeter per second squared (1 cm/s2).