Someone who only feels sexual attraction after forming a strong emotional bond; on the asexual spectrum.
Demisexual sits on the asexual spectrum, in the gray zone between "attraction always" and "attraction never." The AVEN community built the term on a distinction it had been chewing over for years: primary attraction (the spark off someone's face, body, voice — instantly available info) versus secondary attraction (the pull that builds out of knowing a person). A demisexual person mostly runs on the second track. The bond comes first; the attraction, if it comes, comes after. The bond doesn't have to be romantic, and the timeline isn't fixed.
Here's the misconception worth killing: demisexuality is not "being classy," "having standards," or "just waiting for the right person." That's most people describing ordinary caution. Demisexual isn't a dating rule you follow — it's the wiring that decides whether attraction shows up at all. And it's descriptive, not prescriptive: a demisexual person can still choose casual sex; the label maps how attraction works, not what anyone does with it.
If the "so are you basically ace or basically straight" question comes up — that's the whole point of the word existing. The middle needed a name, so the community made one.