permissibly

from WordNet (r) 3.0 (2006)

permissibly
    adv 1: in a permissible manner [syn: {permissibly}, {allowably}]
           [ant: {impermissibly}]

from The Collaborative International Dictionary of English v.0.48

Permissible \Per*mis"si*ble\, a.
   That may be permitted; allowable; admissible. --
   {Per*mis"si*ble*ness}, n. -- {Per*mis"si*bly}, adv.
   [1913 Webster]