Mechanical attachments worn by a character, sometimes grafted directly onto their body. Depending on the amount of separation between the wearer and the exoskeleton, it may sometimes also qualify for the mecha tag.
For organic exoskeletons use carapace.
For a type of weapons/armors in Kakugo no Susume, use Kyouka Gaikokkaku.
Exoskeletons that qualify for mecha:
Exoskeletons that do not qualify for mecha: