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-positive ((of bacteria) being or relating to a bacterium that retains the violet stain used in Gram's method). Gram-negative ((of bacteria) being of or relating to a bacterium that does not retain the violet stain used in Gram's method). Hyponyms (each of the following is a kind of bacteria):