I have few friends of the opposite sex.
It's an age when you become interested in the opposite sex.
noun, noun which may take the genitive case particle 'no'
isomerism
Chemistry term for compounds with the same molecular formula but different structures. Rare in everyday language.
Isomers have different chemical properties.
Once I became a junior high student, I started to become interested in the opposite sex.
He started dating someone of the opposite sex for the first time.
He's popular with the opposite sex because of his cheerful personality.
She's careful about her clothing because she's conscious of how the opposite sex sees her.
nuclear isomer