ANIMDEFS is a lump first introduced in Hexen, which allows texture and flat animation sequences to be defined in WADs rather than being hard-coded in the executable as they are in Doom, Heretic, and Strife. Contrary to the ANIMATED lump in Boom, ANIMDEFS is kept in plain text with no need for a compiler. The number, order, and duration of frames in an animation can be controlled by this lump, including an option for random frame duration.
Vanilla Hexen is limited to a maximum of 20 definitions in ANIMDEFS; the Hexen IWAD's lump defines 16.
ZDoom supports an extended superset of Hexen ANIMDEFS syntax, adding features such as definition of switch textures, door animations in the vein of Strife, and Quake-style warping liquids.