Definitions for half-length
Random House Webster's College Dictionary
something that is only half a full length or height, esp. a portrait of the upper half of the body, including the hands.
(adj.)of half the complete length or height.
Origin of half-length:
a portrait showing the body from only the waist up
representing only the upper half of the body
"a half-length portrait"
abridged to half its original length
of half the whole or ordinary length, as a picture