The Collaborative International Dictionary of English v.0.48:

Abasia \A*ba"si*a\ ([.a]*b[=a]"zh[i^]*[.a]; -z[i^]*[.a]), n.
   [NL.; Gr. 'a- not + ba`sis a step.] (Med.)
   Inability to coordinate muscular actions properly in walking.
   AS [archaic] -- A*ba"sic ([.a]*b[=a]"s[i^]k), a.
   [Webster 1913 Suppl.] Abassi

WordNet (r) 3.0 (2006):

abasia
    n 1: inability to walk