Por"tass (?), n. [OF. porte-hors
a kind of prayer book, so called from being portable; cf. LL.
portiforium.] A breviary; a prayer book. [Written
variously portace, portasse, portesse,
portise, porthose, portos, portus,
portuse, etc.] [Obs.] Spenser. Camden.
By God and by this porthors I you
swear.
Chaucer.