Sex-Indifferent (also called Sex-Neutral) is a term for people who's indifferent toward sex. Most commonly used by Asexual/Ace-spec individuals.
Sex-Indifferent people are not repulsed by sex, but they also do not have any particular positive feelings about sex. For some, this means that they are indifferent toward the idea of being involved in sex themselves, for others it means that they are indifferent toward the idea of sex in general. They may or may nor engage in sexual activities for the pleasure of a partner, or for reproduction, but they have no strong feelings one way or the other about sex.
Some people use Sex-Indifferent and Sex-Ambivalent interchangably, but to many these are distinct experiences. Sex-Ambivalence specifically refers one has complicated or fluctuating feelings regarding sex.
Not all Sex-Indifferent people are Asexual. There are people who are allosexual and Sex-Indifferent.