Reblogging again because there are a couple of other things to note about family terms when you’re looking at pre-C20th literature. (This goes from about the C16th onwards - not read enough 14-15th century stuff to know what it does there.)
Coz, or cousin, can just mean “close family member”. If you read Shakespeare, you’ll see people use it for their siblings, as well as their literal cousins, probably also uncles etc. close in age. Similarly uncle or aunt may be used for people who are technically cousins but are the same age as the speaker’s parents.
Most confusingly, because of Christian marriage vows at the time, since you were effectively becoming “one flesh” with your spouse, and part of the husband’s family in a legal sense, you will find women addressing their husband’s family will often use the term their husband would use, so they’d call their husband’s brother “brother”, rather than “brother-in-law”, similarly for mothers, fathers, and of course cousins. (This is usually gendered - the man isn’t considered in most western European countries of the time to be part of the woman’s family in quite the same way, but you will sometimes see a man use “father” where as a modern reader you’d expect “father-in-law”. It’s also not done all the time - sometimes the “in-law” relationship will be emphasised - in literature, of course, these decisions may be giving you clues about the familial relationships and how much people like each other!) Also then the woman who’s married in to the family will often be called “daughter” by the man’s parents. (Sorry this bit is so binary gendered - but that’s to do with how marriage was defined at the time, and what you’re most likely to find when encountering the literature of the period.)
This is brought to you by being confused by some of this. “Coz” is fine - it’s almost like “pal, but pal that’s family”. It’s when you’re reading or watching some very complicated Shakespeare history play where the dynastic relations are really important, and someone says, “My daughter” and you’re like, “wait, what, is that incest? I thought so-and-so was her father??? oh…….”
