Aceflexible is a category for a type of asexual who rarely experiences or can have experiences similar to sexual attraction without actually experiencing sexual attraction, separating it from greysexualIty. Such as experimenting with sexual activities, but not feeling any attraction or desire and for reasons beyond attraction (cupiosexuality, libido etc). Another example would be an Asexual who associates libido or arousal with sensual attraction, but does not experience sexual attraction. Similar to greysexual, it is very broad and can be both an umbrella term or an identity.
An alternative definition, is one where the term "Aceflexible" has the same meaning as dark greysexual .
History
Aceflexible was first coined in AVEN on February 9th 2013 in a AVEN thread discussing it made by the coiner. It was coined by AVEN user R_1. Aceflexible currently faces issues similar to semisexual to where it's not fully defined and hadn't reached a full understanding. However, if was also controversial during the time of it's creation and people had a lot more of a narrow understanding on sexuality than we do presently today. New identities such as acefluid and aceflux as well as expansion in greysexuality, show that asexuality is a more vast spectrum, and the aceflexible label perhaps could fill a gap for asexuals who do not fit in the grey sexual spectrum.
Resources
https://www.asexuality.org/en/topic/83926-ace-flexible-label/