From LightWiki

Usually refers to the technique of removing stair steps from edges that aren't perfectly horizontal or vertical, by blending the edge using a gradient of colour. The technique is also applicable in LW to remove noise from sampled effects such as photoreal motion blur, depth of field and soft reflections. Antialiasing can be applied to the entire image, or can be selective applied to save time, by only antialiasing pixels that differ from their neighbours by a specified amount. This technique is referred to as adaptive sampling.

Refer also to how antialiasing is controlled in LightWave 9.2.