OK, I got sidetracked into this from a thread elsewhere.

As a Brit, I tend to use knickers to mean a somewhat  looser (though attractive) garment.  Not necessarily the huge baggies of old.  It also has a saucy connotation.

Panties I take to be a generally stretchy skin-tight garment (to my eyes a less attractive design).

And for some reason, while I don't mind 'panties', I hate the word 'panty'.

And while I've never heard them called 'crackers' I would understand the term 'undercrackers'.

Epi