Aceflexible (or Flexible Asexual) refers to those who are mostly asexual and occasionally experience sexual attraction; however, the attraction they experience is so little and/or rare that they consider themselves asexual with sexual fluidity. This would fit the "little to no attraction" definition of asexuality.
The term is identical to nanosexual and can be used interchangeably or used as a synonym. It is sometimes also given the same definition as dark greysexual It is also used to define asexual individuals who are open to the idea of sex, often as a result of wanting to please their romantic partner. This includes those who have experimented with sexual activities, but who have not felt any attraction or desire. Another example would be someone who associates libido/arousal with sensual attraction but does not experience sexual attraction or someone who experiences what can be described as sexual attraction, but who doesn't feel like they fit the sexual category because it was only visual attraction (eg. miransexual, desinosexual).
One may prefer calling themself aceflexible rather than greysexual if they are enigmasexual and can't tell what gender(s) they are attracted to, or because their attraction isn't based on gender. Aceflexible may also be used because one doesn't want to place gender and attraction, or simply feels that they don't have an actual orientation besides asexual.
Similar to greysexual, it is very broad and can be both an umbrella term and an identity. In concept, it is similar to heteroflexible, homoflexible, biflexible, alloflexible, and grayflexible, as one primarily experiences a single orientation with some occasional alterations due to fluidity or other experiences, making it amplusspec.
The term was coined by AVEN user R_1 on February 9, 2013. Aceflexibility, as a concept, was also mentioned by users on AVEN who didn't like the redefining of asexuality as "little to no sexual attraction" rather than "no sexual attraction," and who thought that aceflexibility would make more sense to describe individuals whose attraction is so little and/or rare that it seems nonexistent. This definition was also mentioned consistently in a 2016 thread by AVEN user Starbit in a thread discussing expanding terms in asexuality.
The term "flexible asexual" also refers to an asexual individual who is open to the idea of sex, and it is included as a sub-classification of asexuality on the dating site, Seeking, alongside aromantic asexual and repulsed asexual. The term "flexible asexual" itself was originally coined by Urban Dictionary user AromanticAsexual and was first published and seen on Urban Dictionary on April 17th, 2010.
A similar term, "Asexual-Flexible" was used by mountland of Livejournal to explain his sexual experience, though the definition and descriptions of said post may be better suited to greysexuality than aceflexibility.
The original aceflexible flag was designed by PennedWriters on November 25, 2021. The reversing of the asexual flag represents flexibility or fluidity in asexuality. An alternate flag was created by The Bigender Cosmonaut on the same day and takes aspects from both the asexual flag and the aceflux flag.