Ability word
From MTG Salvation Wiki
An ability word appears in italics at the beginning of some abilities on cards. Ability words are similar to keywords in that they tie together cards that have similar functionality, but they have no special rules meaning and no individual entries in the Comprehensive Rules. Instead, they act as reminders to players. The concept was first seen on tournament legal cards in Odyssey with Threshold, but the concept truly débuted in the Unhinged set with Gotcha!, and was devised by Wizards in order to group similar cards together.
As of October 1, 2009, there are nine ability words in Tournament-legal sets:
There is also Gotcha!, from Unhinged.
An example of an ability word is:
Radiance — {Effect on target [something] that affects all [somethings] that share a color with it.}or
Sweep — Return any number of {Basic Land types} you control to their owner's hand. {An effect based on the number of lands returned.}
