Demisexual is a sexual orientation on the asexual spectrum defined as someone who does not experience sexual attraction until they have formed a deep emotional connection with someone. The connection can be romantic, platonic, or some other form of connection. What counts as a "close connection" can vary between demisexuals. Forming an emotional bond with someone does not mean that one is automatically attracted to said individual, as it just means there's now a possibility for one to feel attraction.

It is important to distinguish between typical sexual attraction to friends and romantic partners, and demisexuality. Additionally, it is important to note that demisexuals are not simply choosing to abstain from sexual activity until they know the individual better. Allosexuals are capable of feeling sexual attraction to individuals they do not know very well, though they typically choose not to act on it. Demisexuals are incapable of feeling sexual attraction unless a close relationship is established, though they may still engage in sexual activity with the assumption that attraction will develop at some point.

Demisexual can be a sexual orientation on its own or can be combined with other orientations. For example, one could be demisexual and polysexual (demipolysexual), meaning that when one does experience sexual attraction they can experience it towards multiple genders, but not all genders.

Demisexual may be considered a type of mesi asexual, greysexual attraction, and aliquasexual attraction. Fraysexual is often described as the "opposite" of demisexual.

Counterparts to demisexual for other forms of attraction include: demiromantic, demiplatonic, demisensual, demialterous, and demiflectic.