Demialterous is an a-spec orientation defined as someone who does not experience alterous attraction until they have formed a deep emotional connection with someone.
Demialterous can be a orientation on its own or can combined with other orientations. For example, one could be demialterous and gay, meaning that when one does experience alterous attraction it's only towards people of the same gender.
The counterparts to demialterous are demisexual, demiromantic, and demiplatonic.
History
The term appears to have been first referenced/used by Pride-Flags on DeviantArt on July 5th, 2015, however it is unknown if this is the original coiner.
The first usage online appears to have been by by DeviantArt user GodofDarness18 on October 7, 2013 in their Pixel Sprite Montage.[1]
Etymology
The prefix demi- means half or partial. The prefix is also used in words such as demigod.
Flag
The flag was made by Pride-Flags on DeviantArt on July 5th, 2015. The light blue represents alterous attraction, while the right facing black triangle is associated with any kind of demi-attraction.