First, I would like to make it clear that bisexuality is a very real and valid identity. Throughout history, bisexuality has been seen as controversial, fake, and invisible because of its lack of positive representation in media. This can have detrimental consequences as "bisexual erasure plays a critical role in reducing access to the resources and support opportunities bisexually oriented people so desperately need," (source). As for every identity, each individual will have their own unique definition of the word. 'Bisexual' quite literally means 'both', but we are aware that there are more than two genders so referring to bisexuality as liking both men and women and only meaning cisgender men and women is transphobic, as it implies that trans women and men are not 'real' women and men. This led to the recently popularized term 'pansexual' - pan meaning 'everything'.
People who identify as bisexual have begun to take back the word and change its meaning to include cis and trans men and women. However, this seemingly leaves out nonbinary/genderqueer/gender non-conforming folx. Many bisexual advocates have widened the definition to include these identities as well, no longer wanting to reinforce the previous exclusivity of the bisexual label. The topic of bisexuality vs. pansexuality can be messy, because of the individualized approach that the LGBTQ+ community has to their identities. There are many people who use the terms bisexual and pansexual interchangeably. One differentiation between the two is that bisexual people love genders that are similar to or different from their own, while pansexual people do not typically have a preference for gender because they love all genders. The gender of a partner does not typically matter to a pansexual person. An excellent illustration of this comes from Robyn Ochs, a bisexual activist, who states on her website, "I call myself bisexual because I acknowledge that I have in myself the potential to be attracted – romantically and/or sexually – to people of more than one sex and/or gender, not necessarily at the same time, not necessarily in the same way, and not necessarily to the same degree" (source). Bottom line: each individual has their own labels and definitions of those labels. If they refer to themselves as bisexual, respect that. If they exclude trans and nonbinary identities from their definition, call them out on their transphobia. However, there should no be pressure to label oneself as 'pansexual' because of the transphobic history of the 'bisexual' label. Bisexuality should imply that trans and nonbinary people are included in their attraction.