"Abyss-" (アビス Abisu) is an archetype of Spell and Trap Cards that support "Mermail" monsters or "Umi".
Due to their Japanese names, a number of monsters (mostly WATER monsters), such as "Abyss Soldier" and "Hot Red Dragon Archfiend Abyss" also fall into this archetype. However, because TCG and OCG support for this archetype only works on Spell and Trap Cards that are not on the field, this is not an issue.
While monsters that are part of the archetype have existed in the TCG and OCG since Spell of Mask and Labyrinth of Nightmare, no support or cards that meet the requirements of support were introduced until Abyss Rising.