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. 1  the basic unit of mass in the metric system, equal to 0.03527 ounce (0.0022046 pound or 15.4321 grains): now defined in the SI system as 0.001 of the mass of the standard international kilogram (a platinum-iridium cylinder kept in France): one pound equals 453.5924 grams: abbrev. g.