The word is not attested elsewhere, and, if genuine, is perhaps an error for raisunable (cf. raisnable), possibly in confusion with preisable.
a.
1(?):
(
c.1185; MS: s.xiii1/3
)
Un mult bon cunseil vus dorai: Li lecheres Jolif est pruz, Saives e mainables a tuz (var. (B: s.xivin) Si amis praisunables a tuz)9932 (var.)
(praisunable) (s.xivin)