afghan. See Afghan, (blanket) Wikipedia:
An afghan is the knitted or crocheted wrap that everyone has seen
thrown over the back of a rocking chair or folded at the foot of
Grandmother's bed. Afghans are often given as gifts and may become
family heirlooms. Many people use an afghan as a throw on a chilly
day, as a bedspread, or as decoration for the back of a chair. An
afghan also makes a good three-season wrap, adding warmth without a
lot of weight.
It's not just a Canadian word and it is in use today, although throw may be more common. See Throws for a Chesterfield Sofa. I have never heard the term throwover. (Native speaker of American English, mostly BosWash corridor.)
The word afghan, referring to a person of Afghanistan, dates to 1831, but the first use of the word to mean the woven blanket was in 1877. I speculate that the word for the blanket fell out of favor with the increasing politicization of the situation in Afghanistan in the late 1970s, but I have not researched this point.