acrocephalopolysyndactyly

condition of together fingers or toes - many of them, and a head that is (like) the highest point, i.e. condition involving several fused fingers or toes and a head that is peak shaped

Breakdown:

highest point, extreme, extremity

used to combine parts

head

used to combine parts

many, much

together, with, concurrent

finger, toe

condition of, quality of, state of, act of