I wonder about the meaning of the word too. I do not know how else to describe the feeling I get when, for instance, my husband brings me out of a bad mood with just a word or a look, I find it difficult to think of any other way to describe the way I respond to him in that situation other than 'submissive'. Likewise the way I feel about doing things I don't particularly care for but that I know will give him pleasure, like cleaning things or wearing the silly underwear that he likes, doing those things makes me feel very strongly submissive.
But there is a lot of stuff I wouldn't do, and perhaps that means I'm not submissive. I wouldn't obey him if he asked me to do something that I really hated the idea of doing. I feel that everyone, no matte how submissive, must have limits. Someone wrote in an article about how she would let her husband tell her what she could eat, for instance, but I feel that there are probably certain things that she wouldn't eat. And even Polly Peachum would, I feel, probably have said 'no' had her Master told her to put her cat in the microwave and fry it.