Wiktionary
strictly proper
a. (context mathematics English) of a transfer function, where the degree of the numerator is less than that of the denominator
Usage examples of "strictly proper".
The blanket had fallen away, baring his body to the waist and exposing more of my own than was strictly proper.
Through an unspoken understanding Metis and Zeus had continued to maintain a strictly proper decorum whenever in the presence of others, and it occurred to Metis that the same might very well be true of Zeus and Dione.