I think "sweaters" in general is better than "knitwear"... because after the knit vs woven, my first impression of "knitwear" is any types of knit, not necessarily a sweater.
Sweater is a sweater made of fussy yarn. A cardigan is an open front sweater, with or without closure (button, hooks, tie, zipper, or none). Pullover is used for sweaters without front opening. It's used, but only to describe a sweater.
A sweater shirt is a the type of athletic wear, I typically refer to the type that looks like fleece but without the fussy fleece backing, if they did, they'd just be "sweats".
Jumper to me actually is short for jumpsuits, so similar to QM posted, but the bottom part is shorts or pants, I guess it can be a skirt as well.