Mrs. Garrett objecting a word Jo used in Scrabble

In the episode where Blair's boyfriend takes Jo to a cotillion, the girls are playing Scrabble and Edna tells Jo 'You can't use that, that's a 4 letter word for' something, and Jo just grins and says 'I know', I always thought she was saying 'four letter word for towel', like toga, but it's been over 10 years since I saw it, does anybody remember what it was?