Cicero in passing in the De Inventione Book II tells us that there are four "parts" of fortitude: magnificence, magnanimity, patience, and perseverance. Patience, he tells us, is "voluntary and sustained endurance, for the sake of what is honourable or advantageous, of difficult and painful labors".
Beyond that passing reference, which will end up being extraordinarily influential, there are few serious discussions of patience over the centuries. One of the important exceptions is De Patientia a treatise attributed to Augustine on the subject. Augustine, if it really is him (scholars have wavered back and forth on the subject), notes that 'patience' is related to the word for suffering, and defines it as "that by which we tolerate evil things with an even mind, that we may not with a mind uneven desert good things, through which we may arrive at better." The patient sufferer finds his suffering lighter than the impatient one, while patience itself contributes to additional goods that would never arise for the impatient. It is undertaken for the sake of good, and thus is not merely suffering in order to suffer. Because patience by its nature is concerned with the mental life, the suffering it deals with need not be physical, but could be anything unpleasant that would goad to wrongdoing. He then goes on to say that it depends on charity and thus cannot be attained by human will alone.
When Thomas Aquinas discusses the virtue of fortitude, he draws on Cicero, as he often does for the others, in order to determine its potential parts -- a potential part being a secondary virtue associated with it, a sort of satellite virtue. Thus the potential parts of fortitude are directly from Cicero's list: magnanimity, magnificence, patience, and perseverance. He develops this idea with respect to patience by combining Cicero's basic idea with much of the argument from the Augustinian De Patientia (2-2.136). Accepting the Augustinian definition of patience, he argues that it is necessarily a lesser virtue than a number of other virtues, including fortitude and temperance, because these virtues deal with greater obstacles to virtue than even hardship and suffering -- death and danger of death in the case of fortitude and pleasures of touch in the case of temperance.
Because the Augustinian treatise discussed whether it is possible to have patience in the proper sense without divine help, Aquinas also considers the question. And he concludes unequivocally that Augustine is right: patience does what it does out of love for good, and the love for good that is sufficient for the kinds of suffering patience must bear must be for a good so great any such suffering is worth it. But suffering is itself a deprivation of good, so the good loved in patience must be a good so great that any ordinary good is inferior to it. Patience, then, does indeed seem to derive from charity, and thus is impossible without grace. It is true that the inclination of reason to good could in principle be great enough, but Aquinas argues that as we actually find it it is always intermixed with the false craving of concupiscence. True patience requires a purity of love that reason alone cannot guarantee. This is not to deny, of course, that someone might endure great suffering for a defective good that he craves; but this kind of endurance of hardship necessarily inherits the defectiveness of the good craved, and thus in any such case would fall short of patience itself.
While Aquinas, following Cicero, places patience as a potential part of fortitude, he does explicitly argue that it has some similarity with temperance. Patience is very much concerned with desires in a way that fortitude is not, for instance, which links it to temperance. In addition, if we understood 'patience' in a very specific sense as concerned with the dangers of death, we could consider it an integral part of fortitude, i.e., an essential condition required for fortitude, rather than a potential part -- the potential part is the kind of patience is more generic, in that it is just concerned with hardship in general rather than with ultimate hardship in particular. He also distinguishes it from the virtue of longanimity; like patience, longanimity is a virtue of endurance, but it is an endurance directed to reaching a good that takes work to reach, and thus it is not particularly concerned with evils or hardships themselves, although the two can be linked insofar as the difficulty of attaining the good could cause grief, and thus suffering. In this sense, one could say that patience involves a sort of constancy combined with longanimity.
Aquinas's synthesis would be quite influential; it is found summarized without attribution, for instance, in Henry More's An Account of Virtue (1701), although parts of More's account of patience, which he regards as a more basic virtue than fortitude, are his own. While the details are not always preserved, 'patience' taken in such a way as at least to suggest a very high standard seems to last until quite late, being easily found even in the early twentieth century. It does not seem to be extant at all anymore -- when we talk about 'patience' it is often more a matter of a particular kind of social etiquette than the sort of everything-for-good devotion that the word once meant. I'm not sure why there is this gap, but my rough sense is that discussion of patience as a virtue in its own right fades a bit through the twentieth century, leaving the moral understanding of the term entirely in the hands of everyday, colloquial conversation.