In discussions of gender identity, which term signifies people who have a sexual interest in one sex?

The term that signifies people who have a sexual interest in one sex is "gay." This term specifically refers to individuals, typically men, who are attracted to members of the same sex. It encompasses a wide range of experiences and identities within the LGBTQ+ community.

Understanding this definition is crucial in discussions of gender identity because it highlights the diversity of sexual orientations and the necessity of recognizing and respecting different experiences. The notion of being "gay" is distinct from other related terms, as it focuses specifically on sexual attraction rather than gender identity or romantic interest alone.

Other terms listed in the question have different meanings: "transgender" relates to individuals whose gender identity differs from the sex they were assigned at birth, "heterosexual" describes individuals attracted to the opposite sex, and "celibate" refers to individuals who choose to abstain from sexual activity regardless of their sexual orientation.