Alterous is an adjective used for an attraction which is neither exclusively platonic or romantic, and for an orientation based in this attraction.
Alterous attraction is described as a desire for emotional closeness, which is not adequately described by romantic or platonic attraction. Alterous attraction may feel like a combination of platonic and romantic, or somewhere in between platonic and romantic on a spectrum, or may feel distinct from either. There may be an associated feeling of discomfort, unease, or just a sense of inaccuracy in labelling themself or their attraction as either wholly romantic or platonic.
Indeed, someone who experiences alterous attraction may experience romantic and/or platonic attractions at different times, with different people, or in different combinations. Alterous attraction may be experienced separately and exclusively from sexual attraction, in addition to sexual attraction, or concurrently with sexual attraction. However, some people may experience attraction exclusively alterously.
Alterous as an orientation label may be used in combination with a prefix, such as bi-, homo-, or demi-. It may also be used as a complete orientation label without a prefix. Someone with an alterous orientation may use other orientation labels to describe other attractions, if they experience other attraction orientations and choose to identify with them.