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.
(gram), Avoid the incorrect abbreviations g., gm, and Gm. A unit of weight in the metric or centesimal system, the equivalent of 15.432358 gr or 0.03527 avoirdupois ounce. gram