A-spec or A-spectrum an umbrella term, describing all identities that fall on the asexual spectrum and aromantic spectrum. The term allow people to talk about those on the ace-spec and the aro-spec at the same time, as the two groups share many common experiences. It is also a useful term for those who are both ace-spec and aro-spec.
The Controversy
According to some individuals using the word a-spec to mean ace/aro-spec is appropriating from autistic individuals, who used the term to mean 'autistic-spectrum'. However there is no evidence that this term ever used. The most common way people tag post about autism is with 'asd' standing for 'autism spectrum disorder' or with the actuallyautistic tag. The word a-spec is currently widely excepted as meaning ace/aro-spec.