Juill - the literal translation of the French word 'slip' is briefs, pants.....and although lingerie is an 8 letter word that would cover this, I don't feel that 'lingerie' is an 'ooh-la-la' type of word. Lingerie is a boring word that describes the area you can buy underwear in a clothes shop, or a collective word for under garments or other dull meanings.
To me, 'ooh-la-la' suggests something slightly naughty or risque and the best I could come up with was knickers !
I see from your message to geo 0939 that you didn't go for knickers! I did try to steer you in the right direction!!! Was that the only one you got wrong.? if so, how very irritating for you! Cheers