n.

1. 性别[U]
   What sex is the baby?

   这婴儿是什么性别？

2. 男性；女性[C]
   There are members of both sexes in the committee.

   委员会里男女委员都有。

3. 性，色情[U]
   There's too much sex in the film.

   这电影里色情场面太多。

4. 性行为，性交；性欲；性感[U]
   American youth in the sixties were rather open about sex.

   六十年代的美国青年对两性关系相当开放。

n.

1. either of the two main categories (male and female) into which humans and most other living things are divided on the basis of their reproductive functions.
   ▸the fact of belonging to one of these categories.
   ▸the group of all members of either sex.
2. sexual activity, specifically sexual intercourse.
   ▸euphemistic a person's genitals.

v.

1. determine the sex of.
2. (sex something up) informal present something in a more interesting or lively way.
3. (sex someone up) informal arouse or attempt to arouse someone sexually.