In architecture, a knee wall is typically a short wall, usually under three feet in height. The term is derived from the association with the vertical location of the human knee. Knee walls are common in old houses that are typically not a full two stories in height, in which the ceiling on the second floor slopes down on one or more sides. These houses are sometimes referred to as one and a half stories.

Also commonly known as a half-wall, buttress or partial-wall

Half-wall=mezza parete:
http://www.castlift.com/cabine/panoramiche.htm

Anche qui si trova il termine inglese e quello italiano:
http://www.westofirelandlifts.com/documents/PlatformLiftsHom...

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Note added at 6 ore (2011-03-19 00:53:12 GMT)
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Ho dimenticato il primo link:
http://en.wikipedia.org/wiki/Knee_wall