Mspec is a term to describe anyone who feels attraction to multiple genders.
"Multiple" + "spectrum."
- Being multisexual (sometimes shortened to m-spec or mspec) means to be any orientation that is part of the multisexual spectrum; To feel attraction to multiple genders. There's great overlap between different mspec identities, and that's okay. Which label a person uses is usually a result of individual preference. - Ezgender Lists, 2021
For a complete list, see Category:Mspec.
M-spec flag by beyond-mogai-pride-flags/arco-pluris
Ambisexual/Multisexual flag (2021, transgentleman-luke/transmasc-transfem-solidarity)